List of publications
Department of Mesoscopic Physics
Department of Quantum Information
Department of Physics of Nanostructures
Department of Theory of Condensed Matter
2022 |
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| 72. | Mir Ali Jafari, Małgorzata Wawrzyniak-Adamczewska, Stefan Stagraczyński, Anna Dyrdał, Józef Barnaś Spin valve effect in two-dimensional VSe2 system J. Magn. Magn. Mater., 548 , pp. 168921, 2022, ISSN: 0304-8853. @article{Jafari2022, title = {Spin valve effect in two-dimensional VSe2 system}, author = {Mir Ali Jafari and Małgorzata Wawrzyniak-Adamczewska and Stefan Stagraczyński and Anna Dyrdał and Józef Barnaś}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321011215?via%3Dihub}, doi = {10.1016/j.jmmm.2021.168921}, issn = {0304-8853}, year = {2022}, date = {2022-03-15}, journal = {J. Magn. Magn. Mater.}, volume = {548}, pages = {168921}, abstract = {Vanadium based dichalcogenides, VSe2, are two-dimensional materials in which magnetic Vanadium atoms are arranged in a hexagonal lattice and are coupled ferromagnetically within the plane. However, adjacent atomic planes are coupled antiferromagnetically. This provides new and interesting opportunities for application in spintronics and data storage and processing technologies. A spin valve magnetoresistance may be achieved when magnetic moments of both atomic planes are driven to parallel alignment by an external magnetic field. The resistance change associated with the transition from antiparallel to parallel configuration is qualitatively similar to that observed in artificially layered metallic magnetic structures. Detailed electronic structure of VSe2 was obtained from DFT calculations. Then, the ballistic spin-valve magnetoresistance was determined within the Landauer formalism. In addition, we also analyze thermal and thermoelectric properties. Both phases of VSe2, denoted as H and T, are considered.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Vanadium based dichalcogenides, VSe2, are two-dimensional materials in which magnetic Vanadium atoms are arranged in a hexagonal lattice and are coupled ferromagnetically within the plane. However, adjacent atomic planes are coupled antiferromagnetically. This provides new and interesting opportunities for application in spintronics and data storage and processing technologies. A spin valve magnetoresistance may be achieved when magnetic moments of both atomic planes are driven to parallel alignment by an external magnetic field. The resistance change associated with the transition from antiparallel to parallel configuration is qualitatively similar to that observed in artificially layered metallic magnetic structures. Detailed electronic structure of VSe2 was obtained from DFT calculations. Then, the ballistic spin-valve magnetoresistance was determined within the Landauer formalism. In addition, we also analyze thermal and thermoelectric properties. Both phases of VSe2, denoted as H and T, are considered. |
| 71. | Andriy E. Serebryannikov, Akhlesh Lakhtakia, Guy A E Vandenbosch, Ekmel Ozbay Scientific Reports, 12 (1), pp. 3518, 2022, ISSN: 2045-2322. @article{Serebryannikov2022, title = {Transmissive terahertz metasurfaces with vanadium dioxide split-rings and grids for switchable asymmetric polarization manipulation}, author = {Andriy E. Serebryannikov and Akhlesh Lakhtakia and Guy A E Vandenbosch and Ekmel Ozbay}, url = {https://doi.org/10.1038/s41598-022-07265-6}, doi = {10.1038/s41598-022-07265-6}, issn = {2045-2322}, year = {2022}, date = {2022-03-03}, journal = {Scientific Reports}, volume = {12}, number = {1}, pages = {3518}, abstract = {Metasurfaces containing arrays of thermally tunable metal-free (double-)split-ring meta-atoms and metal-free grids made of vanadium dioxide (VO$$_2$$), a phase-change material can deliver switching between (1) polarization manipulation in transmission mode as well as related asymmetric transmission and (2) other functionalities in the terahertz regime, especially when operation in the transmission mode is needed to be conserved for both phases of VO$$_2$$. As the meta-atom arrays function as arrays of metallic subwavelength resonators for the metallic phase of VO$$_2$$, but as transmissive phase screens for the insulator phase of VO$$_2$$, numerical simulations of double- and triple-array metasurfaces strongly indicate extreme scenarios of functionality switching also when the resulting structure comprises only VO$$_2$$ meta-atoms and VO$$_2$$ grids. More switching scenarios are achievable when only one meta-atom array or one grid is made of VO$$_2$$ components. They are enabled by the efficient coupling of the geometrically identical resonator arrays/grids that are made of the materials that strongly differ in terms of conductivity, i.e. Cu and VO$$_2$$ in the metallic phase.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Metasurfaces containing arrays of thermally tunable metal-free (double-)split-ring meta-atoms and metal-free grids made of vanadium dioxide (VO$$_2$$), a phase-change material can deliver switching between (1) polarization manipulation in transmission mode as well as related asymmetric transmission and (2) other functionalities in the terahertz regime, especially when operation in the transmission mode is needed to be conserved for both phases of VO$$_2$$. As the meta-atom arrays function as arrays of metallic subwavelength resonators for the metallic phase of VO$$_2$$, but as transmissive phase screens for the insulator phase of VO$$_2$$, numerical simulations of double- and triple-array metasurfaces strongly indicate extreme scenarios of functionality switching also when the resulting structure comprises only VO$$_2$$ meta-atoms and VO$$_2$$ grids. More switching scenarios are achievable when only one meta-atom array or one grid is made of VO$$_2$$ components. They are enabled by the efficient coupling of the geometrically identical resonator arrays/grids that are made of the materials that strongly differ in terms of conductivity, i.e. Cu and VO$$_2$$ in the metallic phase. |
| 70. | Dominika Kuźma, Łukasz Laskowski, Jarosław W. Kłos, Piotr Zieliński Effects of shape on magnetization switching in systems of magnetic elongated nanoparticles J. Magn. Magn. Mat., 545 , pp. 168685, 2022, ISSN: 0304-8853. @article{KUZMA2022168685, title = {Effects of shape on magnetization switching in systems of magnetic elongated nanoparticles}, author = {Dominika Kuźma and Łukasz Laskowski and Jarosław W. Kłos and Piotr Zieliński}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321009215}, doi = {https://doi.org/10.1016/j.jmmm.2021.168685}, issn = {0304-8853}, year = {2022}, date = {2022-03-01}, journal = {J. Magn. Magn. Mat.}, volume = {545}, pages = {168685}, abstract = {The equilibrium magnetization of flat elongated magnetic nanoparticles of different shapes has been determined for a range of the static magnetic fields applied parallel to their long/easy axes. The behaviour of single particles has been compared with that of equidistant chains composed of the same particles. The shapes sharpened at the ends, i.e. elongated diamonds and two-sided swords, switch with minimal inhomogeneities of magnetization and with well rectangular hystereses. This may be useful in designing of binary memory devices. The narrowest hysteresis has been found for hourglass shapes, where the switching is preceded with inhomogeneities of magnetization so the hystereses are rounded. The shapes endowed with broadened heads, such as dumbbells and bones, show vortex-like inhomogeneities, marked with an interesting interplay of helicities, which result in a multi-stage switching with relatively large coercive fields.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The equilibrium magnetization of flat elongated magnetic nanoparticles of different shapes has been determined for a range of the static magnetic fields applied parallel to their long/easy axes. The behaviour of single particles has been compared with that of equidistant chains composed of the same particles. The shapes sharpened at the ends, i.e. elongated diamonds and two-sided swords, switch with minimal inhomogeneities of magnetization and with well rectangular hystereses. This may be useful in designing of binary memory devices. The narrowest hysteresis has been found for hourglass shapes, where the switching is preceded with inhomogeneities of magnetization so the hystereses are rounded. The shapes endowed with broadened heads, such as dumbbells and bones, show vortex-like inhomogeneities, marked with an interesting interplay of helicities, which result in a multi-stage switching with relatively large coercive fields. |
| 69. | Kacper Wrześniewski Journal of Magnetism and Magnetic Materials, 545 , pp. 168703, 2022. @article{Wrześniewski2022b, title = {Interplay of dark states and superconducting correlations in charge transport through quantum dot trimers}, author = {Kacper Wrześniewski}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321009331}, doi = {10.1016/j.jmmm.2021.168703}, year = {2022}, date = {2022-03-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {545}, pages = {168703}, abstract = {Electronic transport through a hybrid triple quantum dot system is theoretically studied by means of the real-time diagrammatic technique in the lowest order of perturbation theory. The central part of the system is arranged in a triangular geometry, with two quantum dots weakly coupled to metallic electrodes, while the third dot is proximitized by an s-wave superconductor. The focus is put on the transport regimes, where one- and two-electron dark states are formed due to the destructive interference of the electronic wavefunctions. This effect greatly influences the properties of the system, leading to the coherent population trapping and consequently to current blockade, negative differential conductance and enhanced shot-noise. It is shown that the presence of the superconducting pairing correlations in the system can lift the dark state blockade and reduce the shot-noise. Moreover, the current oscillations due to the magnetic flux enclosed by the triangular structure and the effect of superconducting correlations are considered. When the dark state has eigenenergy near the chemical potential of superconducting electrode, the amplitude of oscillations is strongly reduced while the current blockade is lifted. However, when the eigenenergy of the dark state is shifted away from the chemical potential of superconducting lead, the current oscillations remain unaffected.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Electronic transport through a hybrid triple quantum dot system is theoretically studied by means of the real-time diagrammatic technique in the lowest order of perturbation theory. The central part of the system is arranged in a triangular geometry, with two quantum dots weakly coupled to metallic electrodes, while the third dot is proximitized by an s-wave superconductor. The focus is put on the transport regimes, where one- and two-electron dark states are formed due to the destructive interference of the electronic wavefunctions. This effect greatly influences the properties of the system, leading to the coherent population trapping and consequently to current blockade, negative differential conductance and enhanced shot-noise. It is shown that the presence of the superconducting pairing correlations in the system can lift the dark state blockade and reduce the shot-noise. Moreover, the current oscillations due to the magnetic flux enclosed by the triangular structure and the effect of superconducting correlations are considered. When the dark state has eigenenergy near the chemical potential of superconducting electrode, the amplitude of oscillations is strongly reduced while the current blockade is lifted. However, when the eigenenergy of the dark state is shifted away from the chemical potential of superconducting lead, the current oscillations remain unaffected. |
| 68. | Kateryna Boboshko, Anna Dyrdał, Józef Barnaś Journal of Magnetism and Magnetic Materials, 545 , pp. 168698, 2022. @article{Boboshko2022, title = {Bilinear magnetoresistance in topological insulators: The role of spin–orbit scattering on impurities}, author = {Kateryna Boboshko and Anna Dyrdał and Józef Barnaś}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321009318}, doi = {10.1016/j.jmmm.2021.168698}, year = {2022}, date = {2022-03-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {545}, pages = {168698}, abstract = {Bilinear magnetoresistance (BMR) is a new kind of magnetoresistance, that scales linearly with electric and magnetic fields. This magnetoresistance occurs in systems with strong spin–orbit interaction. Additionally, this interaction also leads to quadratic magnetoresistance (QMR). We consider theoretically BMR and QMR in surface states of 3D topological insulators, and propose a new mechanism that leads to these effects. This mechanism is based on scattering on spin–orbit impurities. Accordingly, we assume the minimal model of surface electronic states in a single independent surface of a TI, and calculate both BMR and QMR induced as an interplay of current-induced spin polarization (or equivalently effective spin–orbit field) and spin–orbit scattering on impurities. We present detailed characteristics of both BMR and QMR, and compare our results with those obtained for TIs with spin-momentum locking inhomogeneities and hexagonal warping of the Dirac cones.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Bilinear magnetoresistance (BMR) is a new kind of magnetoresistance, that scales linearly with electric and magnetic fields. This magnetoresistance occurs in systems with strong spin–orbit interaction. Additionally, this interaction also leads to quadratic magnetoresistance (QMR). We consider theoretically BMR and QMR in surface states of 3D topological insulators, and propose a new mechanism that leads to these effects. This mechanism is based on scattering on spin–orbit impurities. Accordingly, we assume the minimal model of surface electronic states in a single independent surface of a TI, and calculate both BMR and QMR induced as an interplay of current-induced spin polarization (or equivalently effective spin–orbit field) and spin–orbit scattering on impurities. We present detailed characteristics of both BMR and QMR, and compare our results with those obtained for TIs with spin-momentum locking inhomogeneities and hexagonal warping of the Dirac cones. |
| 67. | Piotr Majek, Krzysztof P. Wójcik,, Ireneusz Weymann Spin-resolved thermal signatures of Majorana-Kondo interplay in double quantum dots Phys. Rev. B, 105 , pp. 075418, 2022. @article{Majek2022b, title = {Spin-resolved thermal signatures of Majorana-Kondo interplay in double quantum dots}, author = {Piotr Majek and Krzysztof P. Wójcik, and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.105.075418}, doi = {10.1103/PhysRevB.105.075418}, year = {2022}, date = {2022-02-17}, journal = {Phys. Rev. B}, volume = {105}, pages = {075418}, abstract = {We investigate theoretically the thermoelectric transport properties of a T-shaped double quantum dot side-coupled to a topological superconducting nanowire hosting Majorana zero-energy modes. The calculations are performed using the numerical renormalization group method focusing on the transport regime, where the system exhibits the two-stage Kondo effect. It is shown that the leakage of Majorana quasiparticles into the double dot system results in a half-suppression of the second stage of the Kondo effect, which is revealed through fractional values of the charge and heat conductances and gives rise to new resonances in the Seebeck coefficient. The heat conductance is found to satisfy a modified Wiedemann-Franz law. Finally, the interplay of Majorana-induced interference with strong electron correlations is discussed in the behavior of the spin Seebeck effect, which is a unique phenomenon of the considered setup.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate theoretically the thermoelectric transport properties of a T-shaped double quantum dot side-coupled to a topological superconducting nanowire hosting Majorana zero-energy modes. The calculations are performed using the numerical renormalization group method focusing on the transport regime, where the system exhibits the two-stage Kondo effect. It is shown that the leakage of Majorana quasiparticles into the double dot system results in a half-suppression of the second stage of the Kondo effect, which is revealed through fractional values of the charge and heat conductances and gives rise to new resonances in the Seebeck coefficient. The heat conductance is found to satisfy a modified Wiedemann-Franz law. Finally, the interplay of Majorana-induced interference with strong electron correlations is discussed in the behavior of the spin Seebeck effect, which is a unique phenomenon of the considered setup. |
| 66. | V. A. Stephanovich, E. V. Kirichenko, V. K. Dugaev, Józef Barnaś Dynamic Friedel oscillations on the surface of a topological insulator Phys. Rev. B, 105 , pp. 075306, 2022. @article{Stephanovich2022, title = {Dynamic Friedel oscillations on the surface of a topological insulator}, author = {V. A. Stephanovich and E. V. Kirichenko and V. K. Dugaev and Józef Barnaś}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.105.075306}, doi = {10.1103/PhysRevB.105.075306}, year = {2022}, date = {2022-02-14}, journal = {Phys. Rev. B}, volume = {105}, pages = {075306}, abstract = {We study theoretically the dynamic Friedel oscillations of electrons at the surface of a topological insulator (TI) that are generated by the rotation of a localized impurity spin. We show that the spin-orbit interaction (SOI) in Rashba form, which is an integral part of the TI Hamiltonian, yields a highly anisotropic response to the localized spin rotation. As a result, the response to a flip of a localized spin z projection involves the reaction of all x, y, and z components of the local magnetization. Additionally, the dynamic spin moment (and thus also Friedel oscillations) emitted by the localized dynamical spin depends on the orientation in the TI plane. The resulting unusual dynamics is due to the interplay of SOI and Ruderman-Kittel-Kasuya-Yoshida interactions. This provides the basis for manipulation of the spin transport in topological insulators decorated with localized impurity spins, which may be important for technological applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We study theoretically the dynamic Friedel oscillations of electrons at the surface of a topological insulator (TI) that are generated by the rotation of a localized impurity spin. We show that the spin-orbit interaction (SOI) in Rashba form, which is an integral part of the TI Hamiltonian, yields a highly anisotropic response to the localized spin rotation. As a result, the response to a flip of a localized spin z projection involves the reaction of all x, y, and z components of the local magnetization. Additionally, the dynamic spin moment (and thus also Friedel oscillations) emitted by the localized dynamical spin depends on the orientation in the TI plane. The resulting unusual dynamics is due to the interplay of SOI and Ruderman-Kittel-Kasuya-Yoshida interactions. This provides the basis for manipulation of the spin transport in topological insulators decorated with localized impurity spins, which may be important for technological applications. |
| 65. | Yuliya S Dadoenkova, Maciej Krawczyk, Igor L Lyubchanskii Opt. Mater. Express, 12 (2), pp. 717–726, 2022. @article{Dadoenkova:22, title = {Goos-Hoenchen shift at Brillouin light scattering by a magnetostatic wave in the Damon-Eshbach configuration [Invited]}, author = {Yuliya S Dadoenkova and Maciej Krawczyk and Igor L Lyubchanskii}, url = {http://opg.optica.org/ome/abstract.cfm?URI=ome-12-2-717}, doi = {10.1364/OME.447984}, year = {2022}, date = {2022-02-12}, journal = {Opt. Mater. Express}, volume = {12}, number = {2}, pages = {717--726}, publisher = {OSA}, abstract = {The lateral shift of an optical beam undergoing Brillouin light scattering by a spin wave propagating along the interface between magnetic and dielectric media (Damon-Eshbach configuration) in the total internal reflection geometry is studied theoretically. Linear and quadratic magneto-optic terms in polarization are taken into account. It is shown that the lateral shift depends on the polarization (s- or p-) state of the scattered electromagnetic wave as well as on the frequency of the spin wave.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The lateral shift of an optical beam undergoing Brillouin light scattering by a spin wave propagating along the interface between magnetic and dielectric media (Damon-Eshbach configuration) in the total internal reflection geometry is studied theoretically. Linear and quadratic magneto-optic terms in polarization are taken into account. It is shown that the lateral shift depends on the polarization (s- or p-) state of the scattered electromagnetic wave as well as on the frequency of the spin wave. |
| 64. | A V Chumak, P Kabos, M Wu, C Abert, C Adelmann, A O Adeyeye, J Akerman, F G Aliev, A Anane, A Awad, C H Back, A Barman, G E W Bauer, M Becherer, E N Beginin, V A S V Bittencourt, Y M Blanter, P Bortolotti, I Boventer, D A Bozhko, S A Bunyaev, J J Carmiggelt, R R Cheenikundil, F Ciubotaru, S Cotofana, G Csaba, O V Dobrovolskiy, C Dubs, M Elyasi, K G Fripp, H Fulara, I A Golovchanskiy, C Gonzalez-Ballestero, Piotr Graczyk, D Grundler, Paweł Gruszecki, G Gubbiotti, K Guslienko, A Haldar, S Hamdioui, R Hertel, B Hillebrands, T Hioki, A Houshang, C -M Hu, H Huebl, M Huth, E Iacocca, M B Jungfleisch, G N Kakazei, A Khitun, R Khymyn, T Kikkawa, M Kloui, O Klein, Jarosław W. Kłos, S Knauer, S Koraltan, M Kostylev, Maciej Krawczyk, I N Krivorotov, V V Kruglyak, D Lachance-Quirion, S Ladak, R Lebrun, Y Li, M Lindner, R Macedo, S Mayr, G A Melkov, Szymon Mieszczak, Y Nakamura, H T Nembach, A A Nikitin, S A Nikitov, V Novosad, J A Otalora, Y Otani, A Papp, B Pigeau, P Pirro, W Porod, F Porrati, H Qin, Bivas Rana, T Reimann, F Riente, O Romero-Isart, A Ross, A V Sadovnikov, A R Safin, E Saitoh, G Schmidt, H Schultheiss, K Schultheiss, A A Serga, S Sharma, J M Shaw, D Suess, O Surzhenko, Krzysztof Szulc, T Taniguchi, M Urbanek, K Usami, A B Ustinov, T van der Sar, S van Dijken, V I Vasyuchka, R Verba, Viola S Kusminskiy, Q Wang, M Weides, M Weiler, S Wintz, S P Wolski, X Zhang Advances in Magnetics Roadmap on Spin-Wave Computing IEEE Trans. Magn., 58 (6), pp. 1-72, 2022, ISSN: 1941-0069. @article{9706176, title = {Advances in Magnetics Roadmap on Spin-Wave Computing}, author = {A V Chumak and P Kabos and M Wu and C Abert and C Adelmann and A O Adeyeye and J Akerman and F G Aliev and A Anane and A Awad and C H Back and A Barman and G E W Bauer and M Becherer and E N Beginin and V A S V Bittencourt and Y M Blanter and P Bortolotti and I Boventer and D A Bozhko and S A Bunyaev and J J Carmiggelt and R R Cheenikundil and F Ciubotaru and S Cotofana and G Csaba and O V Dobrovolskiy and C Dubs and M Elyasi and K G Fripp and H Fulara and I A Golovchanskiy and C Gonzalez-Ballestero and Piotr Graczyk and D Grundler and Paweł Gruszecki and G Gubbiotti and K Guslienko and A Haldar and S Hamdioui and R Hertel and B Hillebrands and T Hioki and A Houshang and C -M Hu and H Huebl and M Huth and E Iacocca and M B Jungfleisch and G N Kakazei and A Khitun and R Khymyn and T Kikkawa and M Kloui and O Klein and Jarosław W. Kłos and S Knauer and S Koraltan and M Kostylev and Maciej Krawczyk and I N Krivorotov and V V Kruglyak and D Lachance-Quirion and S Ladak and R Lebrun and Y Li and M Lindner and R Macedo and S Mayr and G A Melkov and Szymon Mieszczak and Y Nakamura and H T Nembach and A A Nikitin and S A Nikitov and V Novosad and J A Otalora and Y Otani and A Papp and B Pigeau and P Pirro and W Porod and F Porrati and H Qin and Bivas Rana and T Reimann and F Riente and O Romero-Isart and A Ross and A V Sadovnikov and A R Safin and E Saitoh and G Schmidt and H Schultheiss and K Schultheiss and A A Serga and S Sharma and J M Shaw and D Suess and O Surzhenko and Krzysztof Szulc and T Taniguchi and M Urbanek and K Usami and A B Ustinov and T van der Sar and S van Dijken and V I Vasyuchka and R Verba and Viola S Kusminskiy and Q Wang and M Weides and M Weiler and S Wintz and S P Wolski and X Zhang}, doi = {10.1109/TMAG.2022.3149664}, issn = {1941-0069}, year = {2022}, date = {2022-02-07}, journal = {IEEE Trans. Magn.}, volume = {58}, number = {6}, pages = {1-72}, abstract = {Magnonics addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operation in the GHz-to-THz frequency range, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS are just a few of many advantages offered by magnons. Although magnonics is still primarily positioned in the academic domain, the scientific and technological challenges of the field are being extensively investigated, and many proof-of-concept prototypes have already been realized in laboratories. This roadmap is a product of the collective work of many authors, which covers versatile spin-wave computing approaches, conceptual building blocks, and underlying physical phenomena. In particular, the roadmap discusses the computation operations with the Boolean digital data, unconventional approaches, such as neuromorphic computing, and the progress toward magnon-based quantum computing. This article is organized as a collection of sub-sections grouped into seven large thematic sections. Each sub-section is prepared by one or a group of authors and concludes with a brief description of current challenges and the outlook of further development for each research direction.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnonics addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operation in the GHz-to-THz frequency range, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS are just a few of many advantages offered by magnons. Although magnonics is still primarily positioned in the academic domain, the scientific and technological challenges of the field are being extensively investigated, and many proof-of-concept prototypes have already been realized in laboratories. This roadmap is a product of the collective work of many authors, which covers versatile spin-wave computing approaches, conceptual building blocks, and underlying physical phenomena. In particular, the roadmap discusses the computation operations with the Boolean digital data, unconventional approaches, such as neuromorphic computing, and the progress toward magnon-based quantum computing. This article is organized as a collection of sub-sections grouped into seven large thematic sections. Each sub-section is prepared by one or a group of authors and concludes with a brief description of current challenges and the outlook of further development for each research direction. |
| 63. | Agata Krzywicka, Tomasz P Polak Journal of Magnetism and Magnetic Materials, 542 , pp. 168589 , 2022. @article{Krzywicka2022b, title = {Entropy of pair condensed bosons at finite temperatures in optical lattices with bond-charge interaction}, author = {Agata Krzywicka and Tomasz P Polak}, doi = {10.1016/j.jmmm.2021.168589}, year = {2022}, date = {2022-02-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {542}, pages = {168589 }, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 62. | Krzysztof Sobucki, Paweł Gruszecki, Justyna Rychły, Maciej Krawczyk IEEE Transactions on Magnetics, 58 (2), pp. 1-5, 2022, ISSN: 1941-0069. @article{9450803, title = {Control of the Phase of Reflected Spin Waves From Magnonic Gires–Tournois Interferometer of Subwavelength Width}, author = {Krzysztof Sobucki and Paweł Gruszecki and Justyna Rychły and Maciej Krawczyk}, doi = {10.1109/TMAG.2021.3088298}, issn = {1941-0069}, year = {2022}, date = {2022-01-20}, journal = {IEEE Transactions on Magnetics}, volume = {58}, number = {2}, pages = {1-5}, abstract = {The phase is one of the fundamental properties of a wave that allows to control interference effects and can be used to efficiently encode information. We examine numerically a magnonic resonator of the Gires–Tournois interferometer type, which enables the control of the phase of spin waves (SWs) reflected from the edge of the ferromagnetic film. The considered interferometer consists of a Py thin film and a thin, narrow Py stripe placed above its edge, both coupled magnetostatically. We show that the resonances and the phase of the reflected SWs are sensitive for a variation of the geometrical parameters of this bi-layered part of the system. The high sensitivity to film, stripe, and non-magnetic spacer thicknesses offers a prospect for developing magnonic metasurfaces and sensors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The phase is one of the fundamental properties of a wave that allows to control interference effects and can be used to efficiently encode information. We examine numerically a magnonic resonator of the Gires–Tournois interferometer type, which enables the control of the phase of spin waves (SWs) reflected from the edge of the ferromagnetic film. The considered interferometer consists of a Py thin film and a thin, narrow Py stripe placed above its edge, both coupled magnetostatically. We show that the resonances and the phase of the reflected SWs are sensitive for a variation of the geometrical parameters of this bi-layered part of the system. The high sensitivity to film, stripe, and non-magnetic spacer thicknesses offers a prospect for developing magnonic metasurfaces and sensors. |
| 61. | Damian Tomaszewski, Piotr Busz, Jan Martinek Kondo effect in the presence of the spin accumulation and non-equilibrium spin currents Journal of Magnetism and Magnetic Materials, 542 , pp. 168592, 2022. @article{Tomaszewski2022, title = {Kondo effect in the presence of the spin accumulation and non-equilibrium spin currents}, author = {Damian Tomaszewski and Piotr Busz and Jan Martinek}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321008362}, doi = {10.1016/j.jmmm.2021.168592}, year = {2022}, date = {2022-01-15}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {542}, pages = {168592}, abstract = {We present a theoretical description of the spin accumulation effect in metallic Fermi leads on the Kondo effect in the quantum dot attached to those. It has been shown that the spin accumulation by breaking the spin symmetry leads to the suppression of the Kondo effect in some cases. In order to better understand the observed effects, we analyze the spin currents in the system, depending on the spin accumulation of the electrodes, for both symmetrical and anti-symmetrical configuration of spin accumulation. We demonstrate that in the absence of the Kondo resonance splitting the suppression of the Kondo effect is related to the presence of the non-equilibrium spin current in the system.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present a theoretical description of the spin accumulation effect in metallic Fermi leads on the Kondo effect in the quantum dot attached to those. It has been shown that the spin accumulation by breaking the spin symmetry leads to the suppression of the Kondo effect in some cases. In order to better understand the observed effects, we analyze the spin currents in the system, depending on the spin accumulation of the electrodes, for both symmetrical and anti-symmetrical configuration of spin accumulation. We demonstrate that in the absence of the Kondo resonance splitting the suppression of the Kondo effect is related to the presence of the non-equilibrium spin current in the system. |
| 60. | Aleksandra Trzaskowska, P Graczyk, Nandan K. P. Babu, Miłosz Zdunek, H Głowiński, Jarosław W. Kłos, Sławomir Mielcarek The studies on phonons and magnons in [CoFeB/Au]N multilayers of different number of repetitions Journal of Magnetism and Magnetic Materials, 549 , pp. 169049, 2022, ISSN: 0304-8853. @article{TRZASKOWSKA2022169049, title = {The studies on phonons and magnons in [CoFeB/Au]N multilayers of different number of repetitions}, author = {Aleksandra Trzaskowska and P Graczyk and Nandan K. P. Babu and Miłosz Zdunek and H Głowiński and Jarosław W. Kłos and Sławomir Mielcarek}, url = {https://www.sciencedirect.com/science/article/pii/S0304885322000300}, doi = {https://doi.org/10.1016/j.jmmm.2022.169049}, issn = {0304-8853}, year = {2022}, date = {2022-01-13}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {549}, pages = {169049}, abstract = {We investigated the interaction between spin waves and surface acoustic waves in the [CoFeB/Au]N multilayer deposited on the silicon substrate by Brillion light scattering spectroscopy. We showed that this kind of coupling manifested as an anticrossing in magnetoelastic dispersion relation, can be modified by changing the number of repetitions within the multilayer. The observed modification is attributed mostly to the change in the strength of dipolar interactions which alter the dispersion branch of spin wave fundamental mode and shifts the anticrossing towards larger wave vectors where the magnetoelastic coupling is stronger. The studied range of the wave vector was varied between 0.6·105 cm−1 and 2.2·105 cm−1 while the frequency range of investigations was between 3 and 20 GHz.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigated the interaction between spin waves and surface acoustic waves in the [CoFeB/Au]N multilayer deposited on the silicon substrate by Brillion light scattering spectroscopy. We showed that this kind of coupling manifested as an anticrossing in magnetoelastic dispersion relation, can be modified by changing the number of repetitions within the multilayer. The observed modification is attributed mostly to the change in the strength of dipolar interactions which alter the dispersion branch of spin wave fundamental mode and shifts the anticrossing towards larger wave vectors where the magnetoelastic coupling is stronger. The studied range of the wave vector was varied between 0.6·105 cm−1 and 2.2·105 cm−1 while the frequency range of investigations was between 3 and 20 GHz. |
| 59. | Sławomir Mamica Influence of the demagnetizing field on the spin-wave softening in bicomponent magnonic crystals Journal of Magnetism and Magnetic Materials, 546 , pp. 168690, 2022, ISSN: 0304-8853. @article{MAMICA2022168690, title = {Influence of the demagnetizing field on the spin-wave softening in bicomponent magnonic crystals}, author = {Sławomir Mamica}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321009264}, doi = {https://doi.org/10.1016/j.jmmm.2021.168690}, issn = {0304-8853}, year = {2022}, date = {2022-01-05}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {546}, pages = {168690}, abstract = {In bi-component magnonic crystals (MCs) demagnetizing field occurs around interfaces between a matrix and inclusions. As it is already shown this field strongly influences the spin-wave spectrum including the position and the width of band gaps and their response to the change of the external magnetic field. Here, we show its effect on the reversal of the mode order in the spectrum. The reversal of modes means that the modes which are excited mostly in the material with higher saturation magnetization have the lowest frequency than modes excited in the material with low saturation magnetization. We address this effect to the mode-dependent softening of spin waves resulting from the growing influence of the demagnetizing field while the external magnetic field lowers. The effect gives a possibility of the concentration of spin waves (i.e. the spatial distribution of their energy) in one of the constituent materials (the spin wave is excited much stronger in one material than in the other), the matrix or scattering centres, by the external magnetic field. As an example, we study planar bi-component MCs consisting of cobalt inclusions in permalloy matrix, as well as Py inclusions in Co matrix. We show that in both cases lowering external magnetic field drives down in the spectrum these modes which are excited mostly in Co. Moreover, the concentration of such modes in Co is enhanced.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In bi-component magnonic crystals (MCs) demagnetizing field occurs around interfaces between a matrix and inclusions. As it is already shown this field strongly influences the spin-wave spectrum including the position and the width of band gaps and their response to the change of the external magnetic field. Here, we show its effect on the reversal of the mode order in the spectrum. The reversal of modes means that the modes which are excited mostly in the material with higher saturation magnetization have the lowest frequency than modes excited in the material with low saturation magnetization. We address this effect to the mode-dependent softening of spin waves resulting from the growing influence of the demagnetizing field while the external magnetic field lowers. The effect gives a possibility of the concentration of spin waves (i.e. the spatial distribution of their energy) in one of the constituent materials (the spin wave is excited much stronger in one material than in the other), the matrix or scattering centres, by the external magnetic field. As an example, we study planar bi-component MCs consisting of cobalt inclusions in permalloy matrix, as well as Py inclusions in Co matrix. We show that in both cases lowering external magnetic field drives down in the spectrum these modes which are excited mostly in Co. Moreover, the concentration of such modes in Co is enhanced. |
| 58. | Anna Krzyżewska, Anna Dyrdał Physica E, 135 , pp. 114961, 2022, ISSN: 1386-9477. @article{physicaE_2021.114961, title = {Non-equilibrium spin polarization in magnetic two-dimensional electron gas with k-linear and k-cubed Dresselhaus spin–orbit interaction}, author = {Anna Krzyżewska and Anna Dyrdał}, url = {https://doi.org/10.1016/j.physe.2021.114961}, doi = {10.1016/j.physe.2021.114961}, issn = {1386-9477}, year = {2022}, date = {2022-01-01}, journal = {Physica E}, volume = {135}, pages = {114961}, publisher = {North-Holland}, abstract = {The current-induced spin polarization (CISP) of charge carriers is one of the main mechanisms of spin-to-charge interconversion effects that can be used in new spintronics devices. Here, CISP is studied theoreticallyin symmetric quantum wells growing in [001] crystallographic direction, where both𝑘-linear and𝑘-cubedDresselhaus spin–orbit interactions are present. The exchange interaction responsible for perpendicular to planenet magnetization is also taken into account. The main focus is on the influence of cubic Dresselhaus termon CISP and the interplay between spin–orbit interaction (SOI) and the exchange field. The analytical andnumerical results are derived within the linear response theory and Matsubara Green’s function formalism.Apart from detailed numerical results, we also provide some analytical expressions that may be usefulfor interpretation of experimental results and for characterization of quantum wells with Dresselhaus SOI.Analytical expressions for the relevant Berry curvature are also derived, and it is shown that the Berrycurvature in magnetic 2DEG with cubic Dresselhaus interaction oscillates in the𝑘-space, while its averagedvalue is reduced. We also analyze the temperature behavior of CISP and calculate the low-temperature spinpolarizability due to heat current.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The current-induced spin polarization (CISP) of charge carriers is one of the main mechanisms of spin-to-charge interconversion effects that can be used in new spintronics devices. Here, CISP is studied theoreticallyin symmetric quantum wells growing in [001] crystallographic direction, where both𝑘-linear and𝑘-cubedDresselhaus spin–orbit interactions are present. The exchange interaction responsible for perpendicular to planenet magnetization is also taken into account. The main focus is on the influence of cubic Dresselhaus termon CISP and the interplay between spin–orbit interaction (SOI) and the exchange field. The analytical andnumerical results are derived within the linear response theory and Matsubara Green’s function formalism.Apart from detailed numerical results, we also provide some analytical expressions that may be usefulfor interpretation of experimental results and for characterization of quantum wells with Dresselhaus SOI.Analytical expressions for the relevant Berry curvature are also derived, and it is shown that the Berrycurvature in magnetic 2DEG with cubic Dresselhaus interaction oscillates in the𝑘-space, while its averagedvalue is reduced. We also analyze the temperature behavior of CISP and calculate the low-temperature spinpolarizability due to heat current. |
| 57. | Maciej Lewenstein, David Cirauqui, Miguel Angel Garcia-March, Guillem Guigo i Corominas, Przemyslaw R Grzybowski, Jose Saavedra, Martin Wilkens, Jan Wehr Haake-Lewenstein-Wilkens approach to spin-glasses revisited Journal of Physics A: Mathematical and Theoretical, 2022. @article{10.1088/1751-8121/ac9d10, title = {Haake-Lewenstein-Wilkens approach to spin-glasses revisited}, author = {Maciej Lewenstein and David Cirauqui and Miguel Angel Garcia-March and Guillem Guigo i Corominas and Przemyslaw R Grzybowski and Jose Saavedra and Martin Wilkens and Jan Wehr}, url = {http://iopscience.iop.org/article/10.1088/1751-8121/ac9d10}, year = {2022}, date = {2022-01-01}, journal = {Journal of Physics A: Mathematical and Theoretical}, abstract = {We revisit the Haake-Lewenstein-Wilkens (HLW) approach to Edwards-Anderson (EA) model of Ising spin glass [Phys. Rev. Lett. 55, 2606 (1985)]. This approach consists in evaluation and analysis of the probability distribution of configurations of two replicas of the system, averaged over quenched disorder. This probability This approximate result suggest that qEA > 0 at 0 < T < Tc in 3D and 4D. The case of 2D seems to be a little more subtle, since in the present approach energy increase for a domain wall competes with boundary/edge effects more strongly in 2D; still our approach predicts spin glass order at sufficiently low temperature. We speculate, how these predictions confirm/contradict widely spread opinions that: i) There exist only one (up to the spin flip) ground state in EA model in 2D, 3D and 4D; ii) There is (no) spin glass transition in 3D and 4D (2D). This paper is dedicated to the memories of Fritz Haake and Marek Cieplak.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We revisit the Haake-Lewenstein-Wilkens (HLW) approach to Edwards-Anderson (EA) model of Ising spin glass [Phys. Rev. Lett. 55, 2606 (1985)]. This approach consists in evaluation and analysis of the probability distribution of configurations of two replicas of the system, averaged over quenched disorder. This probability This approximate result suggest that qEA > 0 at 0 < T < Tc in 3D and 4D. The case of 2D seems to be a little more subtle, since in the present approach energy increase for a domain wall competes with boundary/edge effects more strongly in 2D; still our approach predicts spin glass order at sufficiently low temperature. We speculate, how these predictions confirm/contradict widely spread opinions that: i) There exist only one (up to the spin flip) ground state in EA model in 2D, 3D and 4D; ii) There is (no) spin glass transition in 3D and 4D (2D). This paper is dedicated to the memories of Fritz Haake and Marek Cieplak. |
2021 |
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| 56. | Fabrizio Minganti, Ievgen I Arkhipov, Adam Miranowicz, Franco Nori Continuous dissipative phase transitions with or without symmetry breaking New Journal of Physics, 23 (12), pp. 122001, 2021. @article{Minganti2021b, title = {Continuous dissipative phase transitions with or without symmetry breaking}, author = {Fabrizio Minganti and Ievgen I Arkhipov and Adam Miranowicz and Franco Nori}, url = {https://doi.org/10.1088/1367-2630/ac3db8}, doi = {10.1088/1367-2630/ac3db8}, year = {2021}, date = {2021-12-22}, journal = {New Journal of Physics}, volume = {23}, number = {12}, pages = {122001}, publisher = {IOP Publishing}, abstract = {The paradigm of second-order phase transitions (PTs) induced by spontaneous symmetry breaking (SSB) in thermal and quantum systems is a pillar of modern physics that has been fruitfully applied to out-of-equilibrium open quantum systems. Dissipative phase transitions (DPTs) of second order are often connected with SSB, in close analogy with well-known thermal second-order PTs in closed quantum and classical systems. That is, a second-order DPT should disappear by preventing the occurrence of SSB. Here, we prove this statement to be wrong, showing that, surprisingly, SSB is not a necessary condition for the occurrence of second-order DPTs in out-of-equilibrium open quantum systems. We analytically prove this result using the Liouvillian theory of DPTs, and demonstrate this anomalous transition in a paradigmatic laser model, where we can arbitrarily remove SSB while retaining criticality, and on a Z2-symmetric model of a two-photon Kerr resonator. This new type of PT cannot be interpreted as a ‘semiclassical’ bifurcation, because, after the DPT, the system steady state remains unique.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The paradigm of second-order phase transitions (PTs) induced by spontaneous symmetry breaking (SSB) in thermal and quantum systems is a pillar of modern physics that has been fruitfully applied to out-of-equilibrium open quantum systems. Dissipative phase transitions (DPTs) of second order are often connected with SSB, in close analogy with well-known thermal second-order PTs in closed quantum and classical systems. That is, a second-order DPT should disappear by preventing the occurrence of SSB. Here, we prove this statement to be wrong, showing that, surprisingly, SSB is not a necessary condition for the occurrence of second-order DPTs in out-of-equilibrium open quantum systems. We analytically prove this result using the Liouvillian theory of DPTs, and demonstrate this anomalous transition in a paradigmatic laser model, where we can arbitrarily remove SSB while retaining criticality, and on a Z2-symmetric model of a two-photon Kerr resonator. This new type of PT cannot be interpreted as a ‘semiclassical’ bifurcation, because, after the DPT, the system steady state remains unique. |
| 55. | Kateřina Jirákov á, Antonín Č, Karel Lemr, Karol Bartkiewicz, Adam Miranowicz Physical Review A, 104 (6), pp. 062436, 2021. @article{Jirakova2021b, title = {Experimental hierarchy and optimal robustness of quantum correlations of two-qubit states with controllable white noise}, author = {Kate{ř}ina Jirákov á and Antonín Č and Karel Lemr and Karol Bartkiewicz and Adam Miranowicz}, url = {https://doi.org/10.1103/physreva.104.062436}, doi = {10.1103/physreva.104.062436}, year = {2021}, date = {2021-12-21}, journal = {Physical Review A}, volume = {104}, number = {6}, pages = {062436}, publisher = {American Physical Society (APS)}, abstract = {We demonstrate a hierarchy of various classes of quantum correlations on experimentally prepared two-qubit Werner-like states with controllable white noise. Werner states, which are white-noise-affected Bell states, are prototypal examples for studying such a hierarchy as a function of the amount of white noise. We experimentally generate Werner states and their generalizations, i.e., partially entangled pure states affected by white noise. These states enable us to study the hierarchy of the following classes of correlations: separability, entanglement, steering in three- and two-measurement scenarios, and Bell nonlocality. We show that the generalized Werner states (GWSs) reveal fundamentally different aspects of the hierarchy compared to the Werner states. In particular, we find five different parameter regimes of the GWSs, including those steerable in a two-measurement scenario but not violating Bell inequalities. This regime cannot be observed for the usual Werner states. Moreover, we find threshold curves separating different regimes of the quantum correlations and find the optimal states which allow for the largest amount of white noise which does not destroy their specific quantum correlations (e.g., unsteerable entanglement). Thus, we could identify the optimal Bell-nondiagonal GWSs which are, for this specific meaning, more robust against the white noise compared to the Bell-diagonal GWSs (i.e., Werner states).}, keywords = {}, pubstate = {published}, tppubtype = {article} } We demonstrate a hierarchy of various classes of quantum correlations on experimentally prepared two-qubit Werner-like states with controllable white noise. Werner states, which are white-noise-affected Bell states, are prototypal examples for studying such a hierarchy as a function of the amount of white noise. We experimentally generate Werner states and their generalizations, i.e., partially entangled pure states affected by white noise. These states enable us to study the hierarchy of the following classes of correlations: separability, entanglement, steering in three- and two-measurement scenarios, and Bell nonlocality. We show that the generalized Werner states (GWSs) reveal fundamentally different aspects of the hierarchy compared to the Werner states. In particular, we find five different parameter regimes of the GWSs, including those steerable in a two-measurement scenario but not violating Bell inequalities. This regime cannot be observed for the usual Werner states. Moreover, we find threshold curves separating different regimes of the quantum correlations and find the optimal states which allow for the largest amount of white noise which does not destroy their specific quantum correlations (e.g., unsteerable entanglement). Thus, we could identify the optimal Bell-nondiagonal GWSs which are, for this specific meaning, more robust against the white noise compared to the Bell-diagonal GWSs (i.e., Werner states). |
| 54. | Fabrizio Minganti, Ievgen I Arkhipov, Adam Miranowicz, Franco Nori Liouvillian spectral collapse in the Scully-Lamb laser model Physical Review Research, 3 (4), pp. 043197, 2021. @article{Minganti2021, title = {Liouvillian spectral collapse in the Scully-Lamb laser model}, author = {Fabrizio Minganti and Ievgen I Arkhipov and Adam Miranowicz and Franco Nori}, url = {https://doi.org/10.1103/physrevresearch.3.043197}, doi = {10.1103/physrevresearch.3.043197}, year = {2021}, date = {2021-12-21}, journal = {Physical Review Research}, volume = {3}, number = {4}, pages = {043197}, publisher = {American Physical Society (APS)}, abstract = {Phase transitions of thermal systems and the laser threshold were first connected more than forty years ago. Despite the nonequilibrium nature of the laser, the Landau theory of thermal phase transitions, applied directly to the Scully-Lamb laser model (SLLM), indicates that the laser threshold is a second-order phase transition, associated with a U(1) spontaneous symmetry breaking (SSB). To capture the genuine nonequilibrium phase transition of the SLLM (i.e., a single-mode laser without a saturable absorber), here we employ a quantum theory of dissipative phase transitions. Our results confirm that the U(1) SSB can occur at the lasing threshold but, in contrast to the Landau theory and semiclassical approximation, they signal that the SLLM “fundamental” transition is a different phenomenon, which we call Liouvillian spectral collapse; that is, the emergence of diabolic points of infinite degeneracy. By considering a generalized SLLM with additional dephasing, we witness a second-order phase transition, with a Liouvillian spectral collapse, but in the absence of symmetry breaking. Most surprisingly, the phase transition corresponds to the emergence of dynamical multistability even without SSB. Normally, bistability is suppressed by quantum fluctuations, while in this case, the very presence of quantum fluctuations enables bistability. This rather anomalous bistability, characterizing the truly dissipative and quantum origin of lasing, can be an experimental signature of our predictions, and we show that it is associated with an emergent dynamical hysteresis.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Phase transitions of thermal systems and the laser threshold were first connected more than forty years ago. Despite the nonequilibrium nature of the laser, the Landau theory of thermal phase transitions, applied directly to the Scully-Lamb laser model (SLLM), indicates that the laser threshold is a second-order phase transition, associated with a U(1) spontaneous symmetry breaking (SSB). To capture the genuine nonequilibrium phase transition of the SLLM (i.e., a single-mode laser without a saturable absorber), here we employ a quantum theory of dissipative phase transitions. Our results confirm that the U(1) SSB can occur at the lasing threshold but, in contrast to the Landau theory and semiclassical approximation, they signal that the SLLM “fundamental” transition is a different phenomenon, which we call Liouvillian spectral collapse; that is, the emergence of diabolic points of infinite degeneracy. By considering a generalized SLLM with additional dephasing, we witness a second-order phase transition, with a Liouvillian spectral collapse, but in the absence of symmetry breaking. Most surprisingly, the phase transition corresponds to the emergence of dynamical multistability even without SSB. Normally, bistability is suppressed by quantum fluctuations, while in this case, the very presence of quantum fluctuations enables bistability. This rather anomalous bistability, characterizing the truly dissipative and quantum origin of lasing, can be an experimental signature of our predictions, and we show that it is associated with an emergent dynamical hysteresis. |
| 53. | Monika Aidelsburger, Luca Barbiero, Alejandro Bermudez, Titas Chanda, Alexandre Dauphin, Daniel González-Cuadra, Przemysław R. Grzybowski, Simon Hands, Fred Jendrzejewski, Johannes Jünemann adn Gediminas Juzeliu ̄nas, Valentin Kasper, Angelo Piga, Shi-Ju Ran, Matteo Rizzi, Germán Sierra, Luca Tagliacozzo, Emanuele Tirrito, Torsten V. Zache, Jakub Zakrzewski, Erez Zohar, Maciej Lewenstein Cold atoms meet lattice gauge theory Philos. Trans. A Math. Phys. Eng. Sci., 380 (2216), pp. 20210064, 2021. @article{Aidelsburger2022-be, title = {Cold atoms meet lattice gauge theory}, author = {Monika Aidelsburger and Luca Barbiero and Alejandro Bermudez and Titas Chanda and Alexandre Dauphin and Daniel González-Cuadra and Przemysław R. Grzybowski and Simon Hands and Fred Jendrzejewski and Johannes Jünemann adn Gediminas Juzeliu ̄nas and Valentin Kasper and Angelo Piga and Shi-Ju Ran and Matteo Rizzi and Germán Sierra and Luca Tagliacozzo and Emanuele Tirrito and Torsten V. Zache and Jakub Zakrzewski and Erez Zohar and Maciej Lewenstein}, url = {https://royalsocietypublishing.org/doi/10.1098/rsta.2021.0064}, doi = {10.1098/rsta.2021.0064}, year = {2021}, date = {2021-12-20}, journal = {Philos. Trans. A Math. Phys. Eng. Sci.}, volume = {380}, number = {2216}, pages = {20210064}, publisher = {The Royal Society}, abstract = {The central idea of this review is to consider quantum field theory models relevant for particle physics and replace the fermionic matter in these models by a bosonic one. This is mostly motivated by the fact that bosons are more áccessible' and easier to manipulate for experimentalists, but this 'substitution' also leads to new physics and novel phenomena. It allows us to gain new information about among other things confinement and the dynamics of the deconfinement transition. We will thus consider bosons in dynamical lattices corresponding to the bosonic Schwinger or [Formula: see text] Bose-Hubbard models. Another central idea of this review concerns atomic simulators of paradigmatic models of particle physics theory such as the Creutz-Hubbard ladder, or Gross-Neveu-Wilson and Wilson-Hubbard models. This article is not a general review of the rapidly growing field-it reviews activities related to quantum simulations for lattice field theories performed by the Quantum Optics Theory group at ICFO and their collaborators from 19 institutions all over the world. Finally, we will briefly describe our efforts to design experimentally friendly simulators of these and other models relevant for particle physics. This article is part of the theme issue 'Quantum technologies in particle physics'.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The central idea of this review is to consider quantum field theory models relevant for particle physics and replace the fermionic matter in these models by a bosonic one. This is mostly motivated by the fact that bosons are more áccessible' and easier to manipulate for experimentalists, but this 'substitution' also leads to new physics and novel phenomena. It allows us to gain new information about among other things confinement and the dynamics of the deconfinement transition. We will thus consider bosons in dynamical lattices corresponding to the bosonic Schwinger or [Formula: see text] Bose-Hubbard models. Another central idea of this review concerns atomic simulators of paradigmatic models of particle physics theory such as the Creutz-Hubbard ladder, or Gross-Neveu-Wilson and Wilson-Hubbard models. This article is not a general review of the rapidly growing field-it reviews activities related to quantum simulations for lattice field theories performed by the Quantum Optics Theory group at ICFO and their collaborators from 19 institutions all over the world. Finally, we will briefly describe our efforts to design experimentally friendly simulators of these and other models relevant for particle physics. This article is part of the theme issue 'Quantum technologies in particle physics'. |
| 52. | Andrzej Grudka, Paweł Kurzyński, Antoni Wójcik Quantum semipermeable barriers: Investigating Maxwell's demon toolbox Physical Review E, 104 , pp. 064114, 2021. @article{Grudka2021, title = {Quantum semipermeable barriers: Investigating Maxwell's demon toolbox}, author = {Andrzej Grudka and Paweł Kurzyński and Antoni Wójcik}, url = {https://journals.aps.org/pre/abstract/10.1103/PhysRevE.104.064114}, doi = {10.1103/PhysRevE.104.064114}, year = {2021}, date = {2021-12-10}, journal = {Physical Review E}, volume = {104}, pages = {064114}, abstract = {We study quantum Maxwell's demon in a discrete space-time setup. We consider a collection of particles hopping on a one-dimensional chain and a semipermeable barrier that allows the particles to hop in only one direction. Our main result is a formulation of a local unitary dynamics describing the action of this barrier. Such dynamics utilizes an auxiliary system A and we study how properties of A influence the behavior of particles. An immediate consequence of unitarity is the fact that particles cannot be trapped on one side of the barrier forever, unless A is infinite. In addition, coherent superpositions and quantum correlations are affected once particles enter the confinement region. Finally, we show that initial superposition of A allows the barrier to act as a beam splitter.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We study quantum Maxwell's demon in a discrete space-time setup. We consider a collection of particles hopping on a one-dimensional chain and a semipermeable barrier that allows the particles to hop in only one direction. Our main result is a formulation of a local unitary dynamics describing the action of this barrier. Such dynamics utilizes an auxiliary system A and we study how properties of A influence the behavior of particles. An immediate consequence of unitarity is the fact that particles cannot be trapped on one side of the barrier forever, unless A is infinite. In addition, coherent superpositions and quantum correlations are affected once particles enter the confinement region. Finally, we show that initial superposition of A allows the barrier to act as a beam splitter. |
| 51. | Jarosław W. Kłos, Maciej Krawczyk, Szymon Mieszczak, Paweł Gruszecki 2021 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS), pp. 518-521, 2021. @inproceedings{9629033, title = {The interplay between spin waves and microwave magnetic field in magnetization textures and planar magnetic nanostructures}, author = {Jarosław W. Kłos and Maciej Krawczyk and Szymon Mieszczak and Paweł Gruszecki}, doi = {10.1109/COMCAS52219.2021.9629033}, year = {2021}, date = {2021-12-06}, booktitle = {2021 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS)}, pages = {518-521}, abstract = {The magnetic microwave field is accompanying the magnetization precession in magnetic materials. However, the precessional dynamics can propagate in the form of the dipolar spin wave only if the magnetic field can effectively mediate the coupling between the magnetic moments at the distance. We refer to counter-intuitive but well known effect - the absence of the dynamic dipolar coupling in an unconstrained and uniformly magnetized medium, to stress the role of the confined geometries and magnetization textures for shaping the dipolar interaction and molding the propagation of the dipolar spin waves. The paper discusses the electromagnetic origin of the dipolar spin waves and explains the role of magnetostatic approximation. Within this approximation, we can introduce the concept of magnetostatic potential, which is very useful for describing of the origin of the dynamic demagnetizing field providing the coupling for the dipolar spin waves.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The magnetic microwave field is accompanying the magnetization precession in magnetic materials. However, the precessional dynamics can propagate in the form of the dipolar spin wave only if the magnetic field can effectively mediate the coupling between the magnetic moments at the distance. We refer to counter-intuitive but well known effect - the absence of the dynamic dipolar coupling in an unconstrained and uniformly magnetized medium, to stress the role of the confined geometries and magnetization textures for shaping the dipolar interaction and molding the propagation of the dipolar spin waves. The paper discusses the electromagnetic origin of the dipolar spin waves and explains the role of magnetostatic approximation. Within this approximation, we can introduce the concept of magnetostatic potential, which is very useful for describing of the origin of the dynamic demagnetizing field providing the coupling for the dipolar spin waves. |
| 50. | Michał Inglot, Vitalii K. Dugaev, Anna Dyrdał, Józef Barnaś Phys. Rev. B, 104 (21), pp. 214408, 2021, ISSN: 2469-9969. @article{Inglot2021, title = {Graphene with Rashba spin-orbit interaction and coupling to a magnetic layer: Electron states localized at the domain wall}, author = {Michał Inglot and Vitalii K. Dugaev and Anna Dyrdał and Józef Barnaś}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.104.214408}, doi = {10.1103/PhysRevB.104.214408}, issn = {2469-9969}, year = {2021}, date = {2021-12-06}, journal = {Phys. Rev. B}, volume = {104}, number = {21}, pages = {214408}, abstract = {Electron states localized at a magnetic domain wall in a graphene with Rashba spin-orbit interaction and coupled to a magnetic layer are studied theoretically. It is shown that two one-dimensional bands of edge modes propagating along the domain wall emerge in the energy gap for each Dirac point, and the modes associated with different Dirac points K and K′ are the same. The coefficients describing decay of the corresponding wave functions with distance from the domain wall contain generally real and imaginary terms. Numerical results on the local spin density and on the total spin expected in the edge states characterized by the wave number ky are presented and discussed. The Chern number for a single magnetic domain on graphene indicates that the system is in the quantum anomalous Hall phase, with two chiral modes at the edges. In turn, the number of modes localized at the domain wall is determined by the difference in Chern numbers on both sides of the wall. These numbers are equal to 2 and −2, respectively, so there are four modes localized at the domain wall.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Electron states localized at a magnetic domain wall in a graphene with Rashba spin-orbit interaction and coupled to a magnetic layer are studied theoretically. It is shown that two one-dimensional bands of edge modes propagating along the domain wall emerge in the energy gap for each Dirac point, and the modes associated with different Dirac points K and K′ are the same. The coefficients describing decay of the corresponding wave functions with distance from the domain wall contain generally real and imaginary terms. Numerical results on the local spin density and on the total spin expected in the edge states characterized by the wave number ky are presented and discussed. The Chern number for a single magnetic domain on graphene indicates that the system is in the quantum anomalous Hall phase, with two chiral modes at the edges. In turn, the number of modes localized at the domain wall is determined by the difference in Chern numbers on both sides of the wall. These numbers are equal to 2 and −2, respectively, so there are four modes localized at the domain wall. |
| 49. | X. Zhou, Elena V. Tartakovskaya, G. N. Kakazei, A. O. Adeyeye Phys. Rev. B, 104 , pp. 214402, 2021. @article{PhysRevB.104.214402, title = {Engineering spin wave spectra in thick Ni80Fe20 rings by using competition between exchange and dipolar fields}, author = {X. Zhou and Elena V. Tartakovskaya and G. N. Kakazei and A. O. Adeyeye}, url = {https://link.aps.org/doi/10.1103/PhysRevB.104.214402}, doi = {10.1103/PhysRevB.104.214402}, year = {2021}, date = {2021-12-03}, journal = {Phys. Rev. B}, volume = {104}, pages = {214402}, publisher = {American Physical Society}, abstract = {Control of the spin wave dynamics in nanomagnetic elements is very important for the realization of a broad range of novel magnonic devices. Here we study experimentally the spin wave resonance in thick ferromagnetic rings (100 nm) using perpendicular ferromagnetic resonance spectroscopy. Different from what was observed for the continuous film of the same thickness, or from rings with similar lateral dimensions but with lower thicknesses, the spectra of thick patterned rings show a nonmonotonic dependence of the mode intensity on the resonance field for a fixed frequency. To explain this effect, the theoretical approach by considering the dependence of the mode profiles on both the radial and axial coordinates was developed. It was demonstrated that such unusual behavior is a result of the competition between exchange and dipolar fields acting at the spin excitations in the structure under study. The calculations are in a good agreement with the experimental results.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Control of the spin wave dynamics in nanomagnetic elements is very important for the realization of a broad range of novel magnonic devices. Here we study experimentally the spin wave resonance in thick ferromagnetic rings (100 nm) using perpendicular ferromagnetic resonance spectroscopy. Different from what was observed for the continuous film of the same thickness, or from rings with similar lateral dimensions but with lower thicknesses, the spectra of thick patterned rings show a nonmonotonic dependence of the mode intensity on the resonance field for a fixed frequency. To explain this effect, the theoretical approach by considering the dependence of the mode profiles on both the radial and axial coordinates was developed. It was demonstrated that such unusual behavior is a result of the competition between exchange and dipolar fields acting at the spin excitations in the structure under study. The calculations are in a good agreement with the experimental results. |
| 48. | Bivas Rana, Amrit Kumar Mondal, Supriyo Bandyopadhyay, Anjan Barman Applications of nanomagnets as dynamical systems - part II Nanotechnology, 33 (8), pp. 082002, 2021. @article{Rana_2021b, title = {Applications of nanomagnets as dynamical systems - part II}, author = {Bivas Rana and Amrit Kumar Mondal and Supriyo Bandyopadhyay and Anjan Barman}, url = {https://doi.org/10.1088/1361-6528/ac2f59}, doi = {10.1088/1361-6528/ac2f59}, year = {2021}, date = {2021-11-30}, journal = {Nanotechnology}, volume = {33}, number = {8}, pages = {082002}, publisher = {IOP Publishing}, abstract = {In Part I of this topical review, we discussed dynamical phenomena in nanomagnets, focusing primarily on magnetization reversal with an eye to digital applications. In this part, we address mostly wave-like phenomena in nanomagnets, with emphasis on spin waves in myriad nanomagnetic systems and methods of controlling magnetization dynamics in nanomagnet arrays which may have analog applications. We conclude with a discussion of some interesting spintronic phenomena that undergird the rich physics exhibited by nanomagnet assemblies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In Part I of this topical review, we discussed dynamical phenomena in nanomagnets, focusing primarily on magnetization reversal with an eye to digital applications. In this part, we address mostly wave-like phenomena in nanomagnets, with emphasis on spin waves in myriad nanomagnetic systems and methods of controlling magnetization dynamics in nanomagnet arrays which may have analog applications. We conclude with a discussion of some interesting spintronic phenomena that undergird the rich physics exhibited by nanomagnet assemblies. |
| 47. | D Kiphart, Y Harkavyi, K Balin, J Szade, Bogusław Mróz, P Kuświk, S Jurga, M Wiesner Scientific Reports, 11 (1), pp. 22980, 2021, ISSN: 2045-2322. @article{kiphart_investigations_2021, title = {Investigations of proximity-induced superconductivity in the topological insulator Bi2Te3 by microRaman spectroscopy}, author = {D Kiphart and Y Harkavyi and K Balin and J Szade and Bogusław Mróz and P Kuświk and S Jurga and M Wiesner}, url = {https://www.nature.com/articles/s41598-021-02475-w}, doi = {10.1038/s41598-021-02475-w}, issn = {2045-2322}, year = {2021}, date = {2021-11-26}, journal = {Scientific Reports}, volume = {11}, number = {1}, pages = {22980}, abstract = {We used the topological insulator (TI) Bi2Te3 and a high-temperature superconductor (HTSC) hybrid device for investigations of proximity-induced superconductivity (PS) in the TI. Application of the superconductor YBa2Cu3O7-δ (YBCO) enabled us to access higher temperature and energy scales for this phenomenon. The HTSC in the hybrid device exhibits emergence of a pseudogap state for T textgreater Tc that converts into a superconducting state with a reduced gap for T textless Tc. The conversion process has been reflected in Raman spectra collected from the TI. Complementary charge transport experiments revealed emergence of the proximity-induced superconducting gap in the TI and the reduced superconducting gap in the HTSC, but no signature of the pseudogap. This allowed us to conclude that Raman spectroscopy reveals formation of the pseudogap state but cannot distinguish the proximity-induced superconducting state in the TI from the superconducting state in the HTSC characterised by the reduced gap. Results of our experiments have shown that Raman spectroscopy is a complementary technique to classic charge transport experiments and is a powerful tool for investigation of the proximity-induced superconductivity in the Bi2Te3.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We used the topological insulator (TI) Bi2Te3 and a high-temperature superconductor (HTSC) hybrid device for investigations of proximity-induced superconductivity (PS) in the TI. Application of the superconductor YBa2Cu3O7-δ (YBCO) enabled us to access higher temperature and energy scales for this phenomenon. The HTSC in the hybrid device exhibits emergence of a pseudogap state for T textgreater Tc that converts into a superconducting state with a reduced gap for T textless Tc. The conversion process has been reflected in Raman spectra collected from the TI. Complementary charge transport experiments revealed emergence of the proximity-induced superconducting gap in the TI and the reduced superconducting gap in the HTSC, but no signature of the pseudogap. This allowed us to conclude that Raman spectroscopy reveals formation of the pseudogap state but cannot distinguish the proximity-induced superconducting state in the TI from the superconducting state in the HTSC characterised by the reduced gap. Results of our experiments have shown that Raman spectroscopy is a complementary technique to classic charge transport experiments and is a powerful tool for investigation of the proximity-induced superconductivity in the Bi2Te3. |
| 46. | Bivas Rana, Amrit Kumar Mondal, Supriyo Bandyopadhyay, Anjan Barman Applications of nanomagnets as dynamical systems - part I Nanotechnology, 33 (6), pp. 062007, 2021. @article{Rana_2021, title = {Applications of nanomagnets as dynamical systems - part I}, author = {Bivas Rana and Amrit Kumar Mondal and Supriyo Bandyopadhyay and Anjan Barman}, url = {https://doi.org/10.1088/1361-6528/ac2e75}, doi = {10.1088/1361-6528/ac2e75}, year = {2021}, date = {2021-11-19}, journal = {Nanotechnology}, volume = {33}, number = {6}, pages = {062007}, publisher = {IOP Publishing}, abstract = {When magnets are fashioned into nanoscale elements, they exhibit a wide variety of phenomena replete with rich physics and the lure of tantalizing applications. In this topical review, we discuss some of these phenomena, especially those that have come to light recently, and highlight their potential applications. We emphasize what drives a phenomenon, what undergirds the dynamics of the system that exhibits the phenomenon, how the dynamics can be manipulated, and what specific features can be harnessed for technological advances. For the sake of balance, we point out both advantages and shortcomings of nanomagnet based devices and systems predicated on the phenomena we discuss. Where possible, we chart out paths for future investigations that can shed new light on an intriguing phenomenon and/or facilitate both traditional and non-traditional applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } When magnets are fashioned into nanoscale elements, they exhibit a wide variety of phenomena replete with rich physics and the lure of tantalizing applications. In this topical review, we discuss some of these phenomena, especially those that have come to light recently, and highlight their potential applications. We emphasize what drives a phenomenon, what undergirds the dynamics of the system that exhibits the phenomenon, how the dynamics can be manipulated, and what specific features can be harnessed for technological advances. For the sake of balance, we point out both advantages and shortcomings of nanomagnet based devices and systems predicated on the phenomena we discuss. Where possible, we chart out paths for future investigations that can shed new light on an intriguing phenomenon and/or facilitate both traditional and non-traditional applications. |
| 45. | Zbigniew Tylczyński Frontiers of Physics, 14 (6), pp. 63301, 2021, ISSN: 2095-0462. @article{tylczynski_collection_2019, title = {A collection of 505 papers on false or unconfirmed ferroelectric properties in single crystals, ceramics and polymers}, author = {Zbigniew Tylczyński}, url = {https://journal.hep.com.cn/fop/EN/10.1007/s11467-019-0912-5}, doi = {10.1007/s11467-019-0912-5}, issn = {2095-0462}, year = {2021}, date = {2021-11-19}, journal = {Frontiers of Physics}, volume = {14}, number = {6}, pages = {63301}, abstract = {textlessptextgreaterThis collection presents 505 papers on ferroelectricity in single crystals, ceramics and polymers in which pointed or elliptical hysteresis loops would testify to their ferroelectric properties. In some papers, the authors ensure that ferroelectricity can occur even in materials that do not have a polar axis of symmetry.textless/ptextgreater}, keywords = {}, pubstate = {published}, tppubtype = {article} } textlessptextgreaterThis collection presents 505 papers on ferroelectricity in single crystals, ceramics and polymers in which pointed or elliptical hysteresis loops would testify to their ferroelectric properties. In some papers, the authors ensure that ferroelectricity can occur even in materials that do not have a polar axis of symmetry.textless/ptextgreater |
| 44. | Paweł Kurzyński Weighted Bures length uncovers quantum state sensitivity Physical Review E, 104 , pp. L052202, 2021. @article{Kurzyński2021, title = {Weighted Bures length uncovers quantum state sensitivity}, author = {Paweł Kurzyński}, url = {https://journals.aps.org/pre/abstract/10.1103/PhysRevE.104.L052202}, doi = {10.1103/PhysRevE.104.L052202}, year = {2021}, date = {2021-11-18}, journal = {Physical Review E}, volume = {104}, pages = {L052202}, abstract = {The unitarity of quantum evolutions implies that an overlap between two initial states does not change in time. This property is commonly believed to explain the apparent lack of state sensitivity in quantum theory, a feature that is prevailing in classical chaotic systems. However, classical state sensitivity is based on a distance between two trajectories in phase space which is a completely different mathematical concept than an overlap between two vectors in Hilbert space. It is possible that state sensitivity in quantum theory can be detected with the help of some special metric. Here we show that the recently introduced Weighted Bures length achieves this task. We numerically investigate a unitary cellular automaton of N interacting qubits and analyze how a single-qubit perturbation affects the evolution of WBL between the unperturbed and perturbed states. We observe a linear growth of WBL if the qubits are arranged into a cyclic graph and an exponential growth if they are arranged into a random bipartite graph.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The unitarity of quantum evolutions implies that an overlap between two initial states does not change in time. This property is commonly believed to explain the apparent lack of state sensitivity in quantum theory, a feature that is prevailing in classical chaotic systems. However, classical state sensitivity is based on a distance between two trajectories in phase space which is a completely different mathematical concept than an overlap between two vectors in Hilbert space. It is possible that state sensitivity in quantum theory can be detected with the help of some special metric. Here we show that the recently introduced Weighted Bures length achieves this task. We numerically investigate a unitary cellular automaton of N interacting qubits and analyze how a single-qubit perturbation affects the evolution of WBL between the unperturbed and perturbed states. We observe a linear growth of WBL if the qubits are arranged into a cyclic graph and an exponential growth if they are arranged into a random bipartite graph. |
| 43. | Marek Vanatka, Krzysztof Szulc, Ondrej Wojewoda, Carsten Dubs, Andrii V Chumak, Maciej Krawczyk, Oleksandr V Dobrovolskiy, Jarosław W. Kłos, Michal Urbánek Spin-Wave Dispersion Measurement by Variable-Gap Propagating Spin-Wave Spectroscopy Phys. Rev. Applied, 16 , pp. 054033, 2021. @article{PhysRevApplied.16.054033, title = {Spin-Wave Dispersion Measurement by Variable-Gap Propagating Spin-Wave Spectroscopy}, author = {Marek Vanatka and Krzysztof Szulc and Ondrej Wojewoda and Carsten Dubs and Andrii V Chumak and Maciej Krawczyk and Oleksandr V Dobrovolskiy and Jarosław W. Kłos and Michal Urbánek}, url = {https://link.aps.org/doi/10.1103/PhysRevApplied.16.054033}, doi = {10.1103/PhysRevApplied.16.054033}, year = {2021}, date = {2021-11-17}, journal = {Phys. Rev. Applied}, volume = {16}, pages = {054033}, publisher = {American Physical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 42. | Hai Xu, Deng-Gao Lai, Yi-Bing Qian, Bang-Pin Hou, Adam Miranowicz, Franco Nori Optomechanical dynamics in the PT- and broken-PT-symmetric regimes Physical Review A, 104 (5), pp. 053518, 2021. @article{Xu2021, title = {Optomechanical dynamics in the PT- and broken-PT-symmetric regimes}, author = {Hai Xu and Deng-Gao Lai and Yi-Bing Qian and Bang-Pin Hou and Adam Miranowicz and Franco Nori}, url = {https://doi.org/10.1103/physreva.104.053518}, doi = {10.1103/physreva.104.053518}, year = {2021}, date = {2021-11-04}, journal = {Physical Review A}, volume = {104}, number = {5}, pages = {053518}, publisher = {American Physical Society (APS)}, abstract = {We theoretically study the dynamics of an optomechanical system, consisting of a passive optical mode and an active mechanical mode, in the PT- and broken-PT-symmetric regimes. By fully analytical treatments for the dynamics of the average displacement and particle numbers, we reveal the phase diagram under different conditions and the various regimes of both PT symmetry and stability of the system. We find that by appropriately tuning either mechanical gain or optomechanical coupling, both phase transitions of the PT symmetry and stability of the system can be flexibly controlled. As a result, the dynamical behaviors of the average displacement, photons, and phonons are radically changed in different regimes. The presented physical mechanism is general and this method can be extended to a general model of dissipative and amplified coupled systems. Our study shows that PT-symmetric optomechanical devices can serve as a powerful tool for the manipulation of mechanical motion, photons, and phonons.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We theoretically study the dynamics of an optomechanical system, consisting of a passive optical mode and an active mechanical mode, in the PT- and broken-PT-symmetric regimes. By fully analytical treatments for the dynamics of the average displacement and particle numbers, we reveal the phase diagram under different conditions and the various regimes of both PT symmetry and stability of the system. We find that by appropriately tuning either mechanical gain or optomechanical coupling, both phase transitions of the PT symmetry and stability of the system can be flexibly controlled. As a result, the dynamical behaviors of the average displacement, photons, and phonons are radically changed in different regimes. The presented physical mechanism is general and this method can be extended to a general model of dissipative and amplified coupled systems. Our study shows that PT-symmetric optomechanical devices can serve as a powerful tool for the manipulation of mechanical motion, photons, and phonons. |
| 41. | Ying Li, Ya-Feng Jiao, Jing-Xue Liu, Adam Miranowicz, Yun-Lan Zuo, Le-Man Kuang, Hui Jing Vector optomechanical entanglement Nanophotonics, 11 (1), pp. 67–77, 2021. @article{Li2021, title = {Vector optomechanical entanglement}, author = {Ying Li and Ya-Feng Jiao and Jing-Xue Liu and Adam Miranowicz and Yun-Lan Zuo and Le-Man Kuang and Hui Jing}, url = {https://doi.org/10.1515/nanoph-2021-0485}, doi = {10.1515/nanoph-2021-0485}, year = {2021}, date = {2021-11-02}, journal = {Nanophotonics}, volume = {11}, number = {1}, pages = {67--77}, abstract = {The polarizations of optical fields, besides field intensities, provide more degrees of freedom to manipulate coherent light–matter interactions. Here, we propose how to achieve a coherent switch of optomechanical entanglement in a polarized-light-driven cavity system. We show that by tuning the polarizations of the driving field, the effective optomechanical coupling can be well controlled and, as a result, quantum entanglement between the mechanical oscillator and the optical transverse electric mode can be coherently and reversibly switched to that between the same phonon mode and the optical transverse magnetic mode. This ability to switch optomechanical entanglement with such a vectorial device can be important for building a quantum network being capable of efficient quantum information interchanges between processing nodes and flying photons.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The polarizations of optical fields, besides field intensities, provide more degrees of freedom to manipulate coherent light–matter interactions. Here, we propose how to achieve a coherent switch of optomechanical entanglement in a polarized-light-driven cavity system. We show that by tuning the polarizations of the driving field, the effective optomechanical coupling can be well controlled and, as a result, quantum entanglement between the mechanical oscillator and the optical transverse electric mode can be coherently and reversibly switched to that between the same phonon mode and the optical transverse magnetic mode. This ability to switch optomechanical entanglement with such a vectorial device can be important for building a quantum network being capable of efficient quantum information interchanges between processing nodes and flying photons. |
| 40. | Cătălin Paşcu Moca, Ireneusz Weymann, Miklós Antal Werner, Gergely Zaránd Kondo Cloud in a Superconductor Phys. Rev. Lett., 127 , pp. 186804, 2021. @article{Moca2021, title = {Kondo Cloud in a Superconductor}, author = {Cătălin Paşcu Moca and Ireneusz Weymann and Miklós Antal Werner and Gergely Zaránd}, url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.186804}, doi = {10.1103/PhysRevLett.127.186804}, year = {2021}, date = {2021-10-27}, journal = {Phys. Rev. Lett.}, volume = {127}, pages = {186804}, abstract = {Magnetic impurities embedded in a metal are screened by the Kondo effect, signaled by the formation of an extended correlation cloud, the so-called Kondo or screening cloud. In a superconductor, the Kondo state turns into subgap Yu-Shiba-Rusinov states, and a quantum phase transition occurs between screened and unscreened phases once the superconducting energy gap Δ exceeds sufficiently the Kondo temperature, TK. Here we show that, although the Kondo state does not form in the unscreened phase, the Kondo cloud does exist in both quantum phases. However, while screening is complete in the screened phase, it is only partial in the unscreened phase. Compensation, a quantity introduced to characterize the integrity of the cloud, is universal, and shown to be related to the magnetic impurities’ g factor, monitored experimentally by bias spectroscopy.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnetic impurities embedded in a metal are screened by the Kondo effect, signaled by the formation of an extended correlation cloud, the so-called Kondo or screening cloud. In a superconductor, the Kondo state turns into subgap Yu-Shiba-Rusinov states, and a quantum phase transition occurs between screened and unscreened phases once the superconducting energy gap Δ exceeds sufficiently the Kondo temperature, TK. Here we show that, although the Kondo state does not form in the unscreened phase, the Kondo cloud does exist in both quantum phases. However, while screening is complete in the screened phase, it is only partial in the unscreened phase. Compensation, a quantity introduced to characterize the integrity of the cloud, is universal, and shown to be related to the magnetic impurities’ g factor, monitored experimentally by bias spectroscopy. |
| 39. | Michal Mruczkiewicz, Paweł Gruszecki The 2021 roadmap for noncollinear magnonics Solid State Physics, 2021, ISSN: 0081-1947. @article{MRUCZKIEWICZ2021, title = {The 2021 roadmap for noncollinear magnonics}, author = {Michal Mruczkiewicz and Paweł Gruszecki}, url = {https://www.sciencedirect.com/science/article/pii/S0081194721000059}, doi = {https://doi.org/10.1016/bs.ssp.2021.09.001}, issn = {0081-1947}, year = {2021}, date = {2021-10-23}, journal = {Solid State Physics}, publisher = {Academic Press}, series = {Solid State Physics}, abstract = {Noncollinear magnonics is a rapidly developing topic of modern magnetism focusing on spin wave (magnon) dynamics in noncollinear spin textures. One of the driving forces of this research field is to employ nanosize dynamical noncollinear spin textures for the control and guiding of magnons. An unquestionable advantage of this approach is the potential to design programmable nanochannels with sizes below patterning limits. Furthermore, the noncollinear magnetic states induce nontrivial dynamical effects suitable for tailoring of SW propagation properties and emission of SWs. In the following, we will summarize the recent achievements of the field and discuss of current and future challenges.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Noncollinear magnonics is a rapidly developing topic of modern magnetism focusing on spin wave (magnon) dynamics in noncollinear spin textures. One of the driving forces of this research field is to employ nanosize dynamical noncollinear spin textures for the control and guiding of magnons. An unquestionable advantage of this approach is the potential to design programmable nanochannels with sizes below patterning limits. Furthermore, the noncollinear magnetic states induce nontrivial dynamical effects suitable for tailoring of SW propagation properties and emission of SWs. In the following, we will summarize the recent achievements of the field and discuss of current and future challenges. |
| 38. | Deng-Gao Lai, Wei Qin, Bang-Pin Hou, Adam Miranowicz, Franco Nori Phys. Rev. A, 104 , pp. 043521, 2021. @article{Lai2021, title = {Significant enhancement in refrigeration and entanglement in auxiliary-cavity-assisted optomechanical systems}, author = {Deng-Gao Lai and Wei Qin and Bang-Pin Hou and Adam Miranowicz and Franco Nori}, url = {https://journals.aps.org/pra/abstract/10.1103/PhysRevA.104.043521}, doi = {10.1103/PhysRevA.104.043521}, year = {2021}, date = {2021-10-22}, journal = {Phys. Rev. A}, volume = {104}, pages = {043521}, abstract = {We propose how to achieve significantly enhanced quantum refrigeration and entanglement by coupling a pumped auxiliary cavity to an optomechanical cavity. We obtain both analytical and numerical results and find optimal-refrigeration and -entanglement conditions under the auxiliary-cavity-assisted (ACA) mechanism. Our method leads to a significant amplification in the net refrigeration rate and reveals that the ACA entanglement has a much stronger noise robustness in comparison with the unassisted case. By appropriately designing the ACA mechanism, an effective mechanical susceptibility can be well adjusted, and a genuine tripartite entanglement of cooling-cavity photons, auxiliary-cavity photons, and phonons can be generated. Specifically, we show that both optomechanical refrigeration and entanglement can be greatly enhanced for the blue-detuned driving of the auxiliary cavity but suppressed for the red-detuned case. Our work paves a way towards further quantum control of macroscopic mechanical systems and the enhancement and protection of fragile quantum resources.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose how to achieve significantly enhanced quantum refrigeration and entanglement by coupling a pumped auxiliary cavity to an optomechanical cavity. We obtain both analytical and numerical results and find optimal-refrigeration and -entanglement conditions under the auxiliary-cavity-assisted (ACA) mechanism. Our method leads to a significant amplification in the net refrigeration rate and reveals that the ACA entanglement has a much stronger noise robustness in comparison with the unassisted case. By appropriately designing the ACA mechanism, an effective mechanical susceptibility can be well adjusted, and a genuine tripartite entanglement of cooling-cavity photons, auxiliary-cavity photons, and phonons can be generated. Specifically, we show that both optomechanical refrigeration and entanglement can be greatly enhanced for the blue-detuned driving of the auxiliary cavity but suppressed for the red-detuned case. Our work paves a way towards further quantum control of macroscopic mechanical systems and the enhancement and protection of fragile quantum resources. |
| 37. | Mateusz Zelent, Iuliia V Vetrova, Jan Šoltýs, Xiaoguang Li, Yan Zhou, Vladislav A Gubanov, Alexandr V Sadovnikov, Tomas Šcepka, Jan Dérer, Roman Stoklas, Vladimír Cambel, Michal Mruczkiewicz Skyrmion Formation in Nanodisks Using Magnetic Force Microscopy Tip Nanomaterials, 11 (10), 2021, ISSN: 2079-4991. @article{nano11102627, title = {Skyrmion Formation in Nanodisks Using Magnetic Force Microscopy Tip}, author = {Mateusz Zelent and Iuliia V Vetrova and Jan Šoltýs and Xiaoguang Li and Yan Zhou and Vladislav A Gubanov and Alexandr V Sadovnikov and Tomas Šcepka and Jan Dérer and Roman Stoklas and Vladimír Cambel and Michal Mruczkiewicz}, url = {https://www.mdpi.com/2079-4991/11/10/2627}, doi = {10.3390/nano11102627}, issn = {2079-4991}, year = {2021}, date = {2021-10-06}, journal = {Nanomaterials}, volume = {11}, number = {10}, abstract = {We demonstrated numerically the skyrmion formation in ultrathin nanodisks using a magnetic force microscopy tip. We found that the local magnetic field generated by the magnetic tip significantly affects the magnetization state of the nanodisks and leads to the formation of skyrmions. Experimentally, we confirmed the influence of the local field on the magnetization states of the disks. Micromagnetic simulations explain the evolution of the magnetic state during magnetic force microscopy scanning and confirm the possibility of skyrmion formation. The formation of the horseshoe magnetic domain is a key transition from random labyrinth domain states into the skyrmion state. We showed that the formation of skyrmions by the magnetic probe is a reliable and repetitive procedure. Our findings provide a simple solution for skyrmion formation in nanodisks.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We demonstrated numerically the skyrmion formation in ultrathin nanodisks using a magnetic force microscopy tip. We found that the local magnetic field generated by the magnetic tip significantly affects the magnetization state of the nanodisks and leads to the formation of skyrmions. Experimentally, we confirmed the influence of the local field on the magnetization states of the disks. Micromagnetic simulations explain the evolution of the magnetic state during magnetic force microscopy scanning and confirm the possibility of skyrmion formation. The formation of the horseshoe magnetic domain is a key transition from random labyrinth domain states into the skyrmion state. We showed that the formation of skyrmions by the magnetic probe is a reliable and repetitive procedure. Our findings provide a simple solution for skyrmion formation in nanodisks. |
| 36. | Damian Tomaszewski, Piotr Busz, Jan Martinek Spin-current Kondo effect: Kondo effect in the presence of spin accumulation Phys. Rev. B, 104 , pp. 125108, 2021. @article{Tomaszewski2021, title = {Spin-current Kondo effect: Kondo effect in the presence of spin accumulation}, author = {Damian Tomaszewski and Piotr Busz and Jan Martinek}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.104.125108}, doi = {10.1103/PhysRevB.104.125108}, year = {2021}, date = {2021-09-07}, journal = {Phys. Rev. B}, volume = {104}, pages = {125108}, abstract = {We present a detailed theoretical description of the influence of the spin accumulation in metallic Fermi leads on the Kondo effect in systems such as quantum dots and Kondo alloys. We discuss an interplay of the spin accumulation, magnetic field, and ferromagnetic leads spin polarization on the Kondo spin-dependent densities of states, conductance, and resistance. It has been shown that the presence of the above-mentioned factors by breaking the spin symmetry leads to the suppression of the Kondo effect. However, for appropriately selected parameter values, these effects can compensate each other, which may lead to the restoration of the Kondo effect in the analyzed systems. We also address some recent experiments related to the spin current in the Kondo alloys.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present a detailed theoretical description of the influence of the spin accumulation in metallic Fermi leads on the Kondo effect in systems such as quantum dots and Kondo alloys. We discuss an interplay of the spin accumulation, magnetic field, and ferromagnetic leads spin polarization on the Kondo spin-dependent densities of states, conductance, and resistance. It has been shown that the presence of the above-mentioned factors by breaking the spin symmetry leads to the suppression of the Kondo effect. However, for appropriately selected parameter values, these effects can compensate each other, which may lead to the restoration of the Kondo effect in the analyzed systems. We also address some recent experiments related to the spin current in the Kondo alloys. |
| 35. | Wei Qin, Adam Miranowicz, Hui Jing, Franco Nori Generating Long-Lived Macroscopically Distinct Superposition States in Atomic Ensembles Phys. Rev. Lett., 127 , pp. 093602, 2021. @article{Qin2021, title = {Generating Long-Lived Macroscopically Distinct Superposition States in Atomic Ensembles}, author = {Wei Qin and Adam Miranowicz and Hui Jing and Franco Nori}, url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.093602}, doi = {10.1103/PhysRevLett.127.093602}, year = {2021}, date = {2021-08-23}, journal = {Phys. Rev. Lett.}, volume = {127}, pages = {093602}, abstract = {We propose to create and stabilize long-lived macroscopic quantum superposition states in atomic ensembles. We show that using a fully quantum parametric amplifier can cause the simultaneous decay of two atoms and, in turn, create stabilized atomic Schrödinger cat states. Remarkably, even with modest parameters these intracavity atomic cat states can have an extremely long lifetime, up to 4 orders of magnitude longer than that of intracavity photonic cat states under the same parameter conditions, reaching tens of milliseconds. This lifetime of atomic cat states is ultimately limited to several seconds by extremely weak spin relaxation and thermal noise. Our work opens up a new way toward the long-standing goal of generating large-size and long-lived cat states, with immediate interests both in fundamental studies and noise-immune quantum technologies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose to create and stabilize long-lived macroscopic quantum superposition states in atomic ensembles. We show that using a fully quantum parametric amplifier can cause the simultaneous decay of two atoms and, in turn, create stabilized atomic Schrödinger cat states. Remarkably, even with modest parameters these intracavity atomic cat states can have an extremely long lifetime, up to 4 orders of magnitude longer than that of intracavity photonic cat states under the same parameter conditions, reaching tens of milliseconds. This lifetime of atomic cat states is ultimately limited to several seconds by extremely weak spin relaxation and thermal noise. Our work opens up a new way toward the long-standing goal of generating large-size and long-lived cat states, with immediate interests both in fundamental studies and noise-immune quantum technologies. |
| 34. | Anjan Barman, Gianluca Gubbiotti, S Ladak, A O Adeyeye, Maciej Krawczyk, J Gräfe, C Adelmann, S Cotofana, A Naeemi, V I Vasyuchka, B Hillebrands, S A Nikitov, H Yu, D Grundler, A V Sadovnikov, A A Grachev, S E Sheshukova, J-Y Duquesne, M Marangolo, G Csaba, W Porod, V E Demidov, S Urazhdin, S O Demokritov, E Albisetti, D Petti, R Bertacco, H Schultheiss, V V Kruglyak, V D Poimanov, S Sahoo, J Sinha, H Yang, M Münzenberg, T Moriyama, S Mizukami, P Landeros, R A Gallardo, G Carlotti, J-V Kim, R L Stamps, R E Camley, Bivas Rana, Y Otani, W Yu, T Yu, G E W Bauer, C Back, G S Uhrig, O V Dobrovolskiy, B Budinska, H Qin, S van Dijken, A V Chumak, A Khitun, D E Nikonov, I A Young, B W Zingsem, M Winklhofer Journal of Physics: Condensed Matter, 33 (41), pp. 413001, 2021. @article{Barman_2021, title = {The 2021 Magnonics Roadmap}, author = {Anjan Barman and Gianluca Gubbiotti and S Ladak and A O Adeyeye and Maciej Krawczyk and J Gräfe and C Adelmann and S Cotofana and A Naeemi and V I Vasyuchka and B Hillebrands and S A Nikitov and H Yu and D Grundler and A V Sadovnikov and A A Grachev and S E Sheshukova and J-Y Duquesne and M Marangolo and G Csaba and W Porod and V E Demidov and S Urazhdin and S O Demokritov and E Albisetti and D Petti and R Bertacco and H Schultheiss and V V Kruglyak and V D Poimanov and S Sahoo and J Sinha and H Yang and M Münzenberg and T Moriyama and S Mizukami and P Landeros and R A Gallardo and G Carlotti and J-V Kim and R L Stamps and R E Camley and Bivas Rana and Y Otani and W Yu and T Yu and G E W Bauer and C Back and G S Uhrig and O V Dobrovolskiy and B Budinska and H Qin and S van Dijken and A V Chumak and A Khitun and D E Nikonov and I A Young and B W Zingsem and M Winklhofer}, url = {https://doi.org/10.1088/1361-648x/abec1a}, doi = {10.1088/1361-648x/abec1a}, year = {2021}, date = {2021-08-18}, journal = {Journal of Physics: Condensed Matter}, volume = {33}, number = {41}, pages = {413001}, publisher = {IOP Publishing}, abstract = {Magnonics is a budding research field in nanomagnetism and nanoscience that addresses the use of spin waves (magnons) to transmit, store, and process information. The rapid advancements of this field during last one decade in terms of upsurge in research papers, review articles, citations, proposals of devices as well as introduction of new sub-topics prompted us to present the first roadmap on magnonics. This is a collection of 22 sections written by leading experts in this field who review and discuss the current status besides presenting their vision of future perspectives. Today, the principal challenges in applied magnonics are the excitation of sub-100 nm wavelength magnons, their manipulation on the nanoscale and the creation of sub-micrometre devices using low-Gilbert damping magnetic materials and its interconnections to standard electronics. To this end, magnonics offers lower energy consumption, easier integrability and compatibility with CMOS structure, reprogrammability, shorter wavelength, smaller device features, anisotropic properties, negative group velocity, non-reciprocity and efficient tunability by various external stimuli to name a few. Hence, despite being a young research field, magnonics has come a long way since its early inception. This roadmap asserts a milestone for future emerging research directions in magnonics, and hopefully, it will inspire a series of exciting new articles on the same topic in the coming years.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnonics is a budding research field in nanomagnetism and nanoscience that addresses the use of spin waves (magnons) to transmit, store, and process information. The rapid advancements of this field during last one decade in terms of upsurge in research papers, review articles, citations, proposals of devices as well as introduction of new sub-topics prompted us to present the first roadmap on magnonics. This is a collection of 22 sections written by leading experts in this field who review and discuss the current status besides presenting their vision of future perspectives. Today, the principal challenges in applied magnonics are the excitation of sub-100 nm wavelength magnons, their manipulation on the nanoscale and the creation of sub-micrometre devices using low-Gilbert damping magnetic materials and its interconnections to standard electronics. To this end, magnonics offers lower energy consumption, easier integrability and compatibility with CMOS structure, reprogrammability, shorter wavelength, smaller device features, anisotropic properties, negative group velocity, non-reciprocity and efficient tunability by various external stimuli to name a few. Hence, despite being a young research field, magnonics has come a long way since its early inception. This roadmap asserts a milestone for future emerging research directions in magnonics, and hopefully, it will inspire a series of exciting new articles on the same topic in the coming years. |
| 33. | Marcin Markiewicz, Marcin Karczewski, Paweł Kurzyński Borromean states in discrete-time quantum walks Quantum, 5 , pp. 523, 2021. @article{Markiewicz2021, title = {Borromean states in discrete-time quantum walks}, author = {Marcin Markiewicz and Marcin Karczewski and Paweł Kurzyński}, url = {https://quantum-journal.org/papers/q-2021-08-16-523/}, doi = {10.22331/q-2021-08-16-523}, year = {2021}, date = {2021-08-16}, journal = {Quantum}, volume = {5}, pages = {523}, abstract = {In the right conditions, removing one particle from a multipartite bound state can make it fall apart. This feature, known as the "Borromean property", has been recently demonstrated experimentally in Efimov states. One could expect that such peculiar behavior should be linked with the presence of strong inter-particle correlations. However, any exploration of this connection is hindered by the complexity of the physical systems exhibiting the Borromean property. To overcome this problem, we introduce a simple dynamical toy model based on a discrete-time quantum walk of many interacting particles. We show that the particles described by it need to exhibit the Greenberger-Horne-Zeillinger (GHZ) entanglement to form Borromean bound states. As this type of entanglement is very prone to particle losses, our work demonstrates an intuitive link between correlations and Borromean properties of the system. Moreover, we discuss our findings in the context of the formation of composite particles.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In the right conditions, removing one particle from a multipartite bound state can make it fall apart. This feature, known as the "Borromean property", has been recently demonstrated experimentally in Efimov states. One could expect that such peculiar behavior should be linked with the presence of strong inter-particle correlations. However, any exploration of this connection is hindered by the complexity of the physical systems exhibiting the Borromean property. To overcome this problem, we introduce a simple dynamical toy model based on a discrete-time quantum walk of many interacting particles. We show that the particles described by it need to exhibit the Greenberger-Horne-Zeillinger (GHZ) entanglement to form Borromean bound states. As this type of entanglement is very prone to particle losses, our work demonstrates an intuitive link between correlations and Borromean properties of the system. Moreover, we discuss our findings in the context of the formation of composite particles. |
| 32. | Piotr Majek, Ireneusz Weymann Majorana mode leaking into a spin-charge entangled double quantum dot Phys. Rev. B, 104 , pp. 085416, 2021. @article{Majek2021, title = {Majorana mode leaking into a spin-charge entangled double quantum dot}, author = {Piotr Majek and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.104.085416}, doi = {10.1103/PhysRevB.104.085416}, year = {2021}, date = {2021-08-12}, journal = {Phys. Rev. B}, volume = {104}, pages = {085416}, abstract = {The signatures of Majorana zero-energy mode leaking into a spin-charge entangled double quantum dot are investigated theoretically in the strong electron correlation regime. The considered setup consists of two capacitively coupled quantum dots attached to external contacts and side-attached to topological superconducting wire hosting Majorana quasiparticles. We show that the presence of Majorana mode gives rise to unique features in the local density of states in the SU(4) Kondo regime. Moreover, it greatly modifies the gate voltage dependence of the linear conductance, leading to fractional values of the conductance. We also analyze the effect of a finite length of topological wire and demonstrate that nonzero overlap of Majorana modes at the ends of the wire is revealed in local extrema present in the local density of states of the dot coupled directly to the wire. The calculations are performed with the aid of the numerical renormalization group method.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The signatures of Majorana zero-energy mode leaking into a spin-charge entangled double quantum dot are investigated theoretically in the strong electron correlation regime. The considered setup consists of two capacitively coupled quantum dots attached to external contacts and side-attached to topological superconducting wire hosting Majorana quasiparticles. We show that the presence of Majorana mode gives rise to unique features in the local density of states in the SU(4) Kondo regime. Moreover, it greatly modifies the gate voltage dependence of the linear conductance, leading to fractional values of the conductance. We also analyze the effect of a finite length of topological wire and demonstrate that nonzero overlap of Majorana modes at the ends of the wire is revealed in local extrema present in the local density of states of the dot coupled directly to the wire. The calculations are performed with the aid of the numerical renormalization group method. |
| 31. | Veysel Erçağlar, Hodjat Hajian, Andriy E. Serebryannikov, Ekmel Ozbay Multifunctional tunable gradient metasurfaces for terahertz beam splitting and light absorption Opt. Lett., 46 (16), pp. 3953–3956, 2021. @article{Ercaglar:21, title = {Multifunctional tunable gradient metasurfaces for terahertz beam splitting and light absorption}, author = {Veysel Erçağlar and Hodjat Hajian and Andriy E. Serebryannikov and Ekmel Ozbay}, url = {http://ol.osa.org/abstract.cfm?URI=ol-46-16-3953}, doi = {10.1364/OL.435197}, year = {2021}, date = {2021-08-09}, journal = {Opt. Lett.}, volume = {46}, number = {16}, pages = {3953--3956}, publisher = {OSA}, abstract = {Obtaining functional devices with tunable features is beneficial to advance terahertz (THz) science and technology. Here, we propose multifunctional gradient metasurfaces that are composed of a periodic array of binary Si microcylinders integrated with VO2 and graphene. The metasurfaces act as transmittive (reflective) beamsplitters for the dielectric (metallic) phase of VO2 with a switchable characteristic. Moreover, by integrating the metasurfaces with graphene and modifying its chemical potential, one can tune the intensity of the split beam as well as obtain nearly perfect resonant absorptions. Consequently, the proposed metasurfaces can find potential applications in THz interferometers, multiplexers, and light absorbers.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Obtaining functional devices with tunable features is beneficial to advance terahertz (THz) science and technology. Here, we propose multifunctional gradient metasurfaces that are composed of a periodic array of binary Si microcylinders integrated with VO2 and graphene. The metasurfaces act as transmittive (reflective) beamsplitters for the dielectric (metallic) phase of VO2 with a switchable characteristic. Moreover, by integrating the metasurfaces with graphene and modifying its chemical potential, one can tune the intensity of the split beam as well as obtain nearly perfect resonant absorptions. Consequently, the proposed metasurfaces can find potential applications in THz interferometers, multiplexers, and light absorbers. |
| 30. | Piotr Graczyk, Maciej Krawczyk Scientific Reports, 11 (1), pp. 15692, 2021. @article{graczyk_nonresonant_2021, title = {Nonresonant amplification of spin waves through interface magnetoelectric effect and spin-transfer torque}, author = {Piotr Graczyk and Maciej Krawczyk}, url = {https://www.nature.com/articles/s41598-021-95267-1}, doi = {10.1038/s41598-021-95267-1}, year = {2021}, date = {2021-08-03}, urldate = {2021-08-03}, journal = {Scientific Reports}, volume = {11}, number = {1}, pages = {15692}, abstract = {We present a new mechanism for manipulation of the spin-wave amplitude through the use of the dynamic charge-mediated magnetoelectric effect in ultrathin multilayers composed of dielectric thin-film capacitors separated by a ferromagnetic bilayer. Propagating spin waves can be amplified and attenuated with rising and decreasing slopes of the oscillating voltage, respectively, locally applied to the sample. The way the spin accumulation is generated makes the interaction of the spin-transfer torque with the magnetization dynamics mode-selective and restricted to some range of spin-wave frequencies, which is contrary to known types of the spin-transfer torque effects. The interfacial nature of spin-dependent screening allows to reduce the thickness of the fixed magnetization layer to a few nanometers, thus the proposed effect significantly contributes toward realization of the magnonic devices and also miniaturization of the spintronic devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present a new mechanism for manipulation of the spin-wave amplitude through the use of the dynamic charge-mediated magnetoelectric effect in ultrathin multilayers composed of dielectric thin-film capacitors separated by a ferromagnetic bilayer. Propagating spin waves can be amplified and attenuated with rising and decreasing slopes of the oscillating voltage, respectively, locally applied to the sample. The way the spin accumulation is generated makes the interaction of the spin-transfer torque with the magnetization dynamics mode-selective and restricted to some range of spin-wave frequencies, which is contrary to known types of the spin-transfer torque effects. The interfacial nature of spin-dependent screening allows to reduce the thickness of the fixed magnetization layer to a few nanometers, thus the proposed effect significantly contributes toward realization of the magnonic devices and also miniaturization of the spintronic devices. |
| 29. | Xiao-Xiao Chen, Zhe Meng, Jian Li, Jia-Zhi Yang, An-Ning Zhang, Tomasz Kopyciuk, Paweł Kurzyński Nonclassical oscillations in pre- and post-selected quantum walks Phys. Rev. A, 104 , pp. 012220, 2021. @article{PhysRevA.104.012220, title = {Nonclassical oscillations in pre- and post-selected quantum walks}, author = {Xiao-Xiao Chen and Zhe Meng and Jian Li and Jia-Zhi Yang and An-Ning Zhang and Tomasz Kopyciuk and Paweł Kurzyński}, url = {https://link.aps.org/doi/10.1103/PhysRevA.104.012220}, doi = {10.1103/PhysRevA.104.012220}, year = {2021}, date = {2021-07-28}, journal = {Phys. Rev. A}, volume = {104}, pages = {012220}, publisher = {American Physical Society}, abstract = {Quantum walks are counterparts of classical random walks. They spread faster, which can be exploited in information processing tasks, and constitute a versatile simulation platform for many quantum systems. Yet, some of their properties can be emulated with classical light. This raises a question: which aspects of the model are truly nonclassical? We address it by carrying out a photonic experiment based on a pre- and post-selection paradox. The paradox implies that if somebody could choose to ask either if the particle is at position x = 0 at even time steps or at position x = d (d > 1) at odd time steps, the answer would be positive, no matter the question asked. Therefore, the particle seems to undergo long distance oscillations despite the fact that the model allows it to jump one position at a time. We translate this paradox into a Bell-like inequality and then into a contextuality witness. Finally, we experimentally verify this witness up to eight standard deviations.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Quantum walks are counterparts of classical random walks. They spread faster, which can be exploited in information processing tasks, and constitute a versatile simulation platform for many quantum systems. Yet, some of their properties can be emulated with classical light. This raises a question: which aspects of the model are truly nonclassical? We address it by carrying out a photonic experiment based on a pre- and post-selection paradox. The paradox implies that if somebody could choose to ask either if the particle is at position x = 0 at even time steps or at position x = d (d > 1) at odd time steps, the answer would be positive, no matter the question asked. Therefore, the particle seems to undergo long distance oscillations despite the fact that the model allows it to jump one position at a time. We translate this paradox into a Bell-like inequality and then into a contextuality witness. Finally, we experimentally verify this witness up to eight standard deviations. |
| 28. | Aleksandra Trzaskowska, Sławomir Mielcarek, M Wiesner, F Lombardi, Bogusław Mróz Ultrasonics, 117 , pp. 106526, 2021. @article{TRZASKOWSKA2021106526, title = {Dispersion of the surface phonons in semiconductor/topological insulator Si/Bi2Te3 heterostructure studied by high resolution Brillouin spectroscopy}, author = {Aleksandra Trzaskowska and Sławomir Mielcarek and M Wiesner and F Lombardi and Bogusław Mróz}, url = {https://www.sciencedirect.com/science/article/pii/S0041624X21001554}, doi = {https://doi.org/10.1016/j.ultras.2021.106526}, year = {2021}, date = {2021-07-21}, journal = {Ultrasonics}, volume = {117}, pages = {106526}, abstract = {The dynamics and dispersion of surface phonons in heterostructure semiconductor/ topological insulator Si/Bi2Te3 was investigated using high resolution Brillouin light scattering method in the GHz frequency range. Both Rayleigh and Sezawa surface acoustic waves have been observed for wave vectors ranging from 0.006 to 0.023 nm−1. Anomaly in dispersion relations ω(q) for both surface waves were detected for the wave vector q = 0.016 nm−1. The finite element method (FEM) was used to simulate the observed shapes of ω(q) and to find the deformation profiles of surface acoustic waves. We attribute the observed changes to the coupling between low energy electrons and surface phonons. The coupling between helical Dirac states and surface phonons is discussed in the frame of accessible theoretical models.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The dynamics and dispersion of surface phonons in heterostructure semiconductor/ topological insulator Si/Bi2Te3 was investigated using high resolution Brillouin light scattering method in the GHz frequency range. Both Rayleigh and Sezawa surface acoustic waves have been observed for wave vectors ranging from 0.006 to 0.023 nm−1. Anomaly in dispersion relations ω(q) for both surface waves were detected for the wave vector q = 0.016 nm−1. The finite element method (FEM) was used to simulate the observed shapes of ω(q) and to find the deformation profiles of surface acoustic waves. We attribute the observed changes to the coupling between low energy electrons and surface phonons. The coupling between helical Dirac states and surface phonons is discussed in the frame of accessible theoretical models. |
| 27. | Pontus Laurell, Allen Scheie, Chiron J Mukherjee, Michael M Koza, Mechtild Enderle, Zbigniew Tylczyński, Satoshi Okamoto, Radu Coldea, Alan D Tennant, Gonzalo Alvarez Quantifying and Controlling Entanglement in the Quantum Magnet Cs2CoCl4 Phys. Rev. Lett., 127 , pp. 037201, 2021. @article{PhysRevLett.127.037201, title = {Quantifying and Controlling Entanglement in the Quantum Magnet Cs2CoCl4}, author = {Pontus Laurell and Allen Scheie and Chiron J Mukherjee and Michael M Koza and Mechtild Enderle and Zbigniew Tylczyński and Satoshi Okamoto and Radu Coldea and Alan D Tennant and Gonzalo Alvarez}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.127.037201}, doi = {10.1103/PhysRevLett.127.037201}, year = {2021}, date = {2021-07-13}, journal = {Phys. Rev. Lett.}, volume = {127}, pages = {037201}, publisher = {American Physical Society}, abstract = {The lack of methods to experimentally detect and quantify entanglement in quantum matter impedes our ability to identify materials hosting highly entangled phases, such as quantum spin liquids. We thus investigate the feasibility of using inelastic neutron scattering (INS) to implement a model-independent measurement protocol for entanglement based on three entanglement witnesses: one-tangle, two-tangle, and quantum Fisher information (QFI). We perform high-resolution INS measurements on Cs2CoCl4, a close realization of the S=1/2 transverse-field XXZ spin chain, where we can control entanglement using the magnetic field, and compare with density-matrix renormalization group calculations for validation. The three witnesses allow us to infer entanglement properties and make deductions about the quantum state in the material. We find QFI to be a particularly robust experimental probe of entanglement, whereas the one and two-tangles require more careful analysis. Our results lay the foundation for a general entanglement detection protocol for quantum spin systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The lack of methods to experimentally detect and quantify entanglement in quantum matter impedes our ability to identify materials hosting highly entangled phases, such as quantum spin liquids. We thus investigate the feasibility of using inelastic neutron scattering (INS) to implement a model-independent measurement protocol for entanglement based on three entanglement witnesses: one-tangle, two-tangle, and quantum Fisher information (QFI). We perform high-resolution INS measurements on Cs2CoCl4, a close realization of the S=1/2 transverse-field XXZ spin chain, where we can control entanglement using the magnetic field, and compare with density-matrix renormalization group calculations for validation. The three witnesses allow us to infer entanglement properties and make deductions about the quantum state in the material. We find QFI to be a particularly robust experimental probe of entanglement, whereas the one and two-tangles require more careful analysis. Our results lay the foundation for a general entanglement detection protocol for quantum spin systems. |
| 26. | Patrycja Tulewicz, Kacper Wrześniewski, Szabolcs Csonka, Ireneusz Weymann Large Voltage-Tunable Spin Valve Based on a Double Quantum Dot Phys. Rev. Applied, 16 , pp. 014029, 2021. @article{Tulewicz2021, title = {Large Voltage-Tunable Spin Valve Based on a Double Quantum Dot}, author = {Patrycja Tulewicz and Kacper Wrześniewski and Szabolcs Csonka and Ireneusz Weymann}, url = {https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.16.014029}, doi = {https://doi.org/10.1103/PhysRevApplied.16.014029}, year = {2021}, date = {2021-07-12}, journal = {Phys. Rev. Applied}, volume = {16}, pages = {014029}, abstract = {We study the spin-dependent transport properties of a spin valve based on a double quantum dot. Each quantum dot is assumed to be strongly coupled to its own ferromagnetic lead, while the coupling between the dots is relatively weak. The current flowing through the system is determined within perturbation theory in the hopping between the dots, whereas the spectrum of a quantum-dot–ferromagnetic-lead subsystem is determined by means of the numerical renormalization group method. The spin-dependent charge fluctuations between ferromagnets and quantum dots generate an effective exchange field, which splits the double-dot levels. Such a field can be controlled, separately for each quantum dot, by the gate voltages or by changing the magnetic configuration of the external leads. We demonstrate that the considered double-quantum-dot spin-valve setup exhibits enhanced magnetoresistive properties, including both normal and inverse tunnel magnetoresistance. We also show that this system allows for the generation of highly spin-polarized currents, which can be controlled by purely electrical means. The considered double quantum dot with ferromagnetic contacts can thus serve as an efficient voltage-tunable spin valve characterized by high output parameters.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We study the spin-dependent transport properties of a spin valve based on a double quantum dot. Each quantum dot is assumed to be strongly coupled to its own ferromagnetic lead, while the coupling between the dots is relatively weak. The current flowing through the system is determined within perturbation theory in the hopping between the dots, whereas the spectrum of a quantum-dot–ferromagnetic-lead subsystem is determined by means of the numerical renormalization group method. The spin-dependent charge fluctuations between ferromagnets and quantum dots generate an effective exchange field, which splits the double-dot levels. Such a field can be controlled, separately for each quantum dot, by the gate voltages or by changing the magnetic configuration of the external leads. We demonstrate that the considered double-quantum-dot spin-valve setup exhibits enhanced magnetoresistive properties, including both normal and inverse tunnel magnetoresistance. We also show that this system allows for the generation of highly spin-polarized currents, which can be controlled by purely electrical means. The considered double quantum dot with ferromagnetic contacts can thus serve as an efficient voltage-tunable spin valve characterized by high output parameters. |
| 25. | Ievgen I Arkhipov, Fabrizio Minganti, Adam Miranowicz, Franco Nori Generating high-order quantum exceptional points in synthetic dimensions Physical Review A, 104 (1), pp. 012205, 2021. @article{Arkhipov2021b, title = {Generating high-order quantum exceptional points in synthetic dimensions}, author = {Ievgen I Arkhipov and Fabrizio Minganti and Adam Miranowicz and Franco Nori}, url = {https://doi.org/10.1103/physreva.104.012205}, doi = {10.1103/physreva.104.012205}, year = {2021}, date = {2021-07-08}, journal = {Physical Review A}, volume = {104}, number = {1}, pages = {012205}, publisher = {American Physical Society (APS)}, abstract = {Recently, there has been intense research in proposing and developing various methods for constructing high-order exceptional points (EPs) in dissipative systems. These EPs can possess a number of intriguing properties related to, e.g., chiral transport and enhanced sensitivity. Previous proposals to realize non-Hermitian Hamiltonians (NHHs) with high-order EPs have been mainly based on either direct construction of spatial networks of coupled modes or utilization of synthetic dimensions, e.g., mapping of spatial lattices to time or photon-number space. Both methods rely on the construction of effective NHHs describing classical or postselected quantum fields, which neglect the effects of quantum jumps and which, thus, suffer from a scalability problem in the quantum regime, when the probability of quantum jumps increases with the number of excitations and dissipation rate. Here, by considering the full quantum dynamics of a quadratic Liouvillian superoperator, we introduce a simple and effective method for engineering NHHs with high-order quantum EPs, derived from evolution matrices of system operator moments. That is, by quantizing higher-order moments of system operators, e.g., of a quadratic two-mode system, the resulting evolution matrices can be interpreted as alternative NHHs describing, e.g., a spatial lattice of coupled resonators, where spatial sites are represented by high-order field moments in the synthetic space of field moments. Notably, such a mapping allows correct reproduction of the results of the Liouvillian dynamics, including quantum jumps. As an example, we consider a U(1)-symmetric quadratic Liouvillian describing a bimodal cavity with incoherent mode coupling, which can also possess anti−PT symmetry, whose field moment dynamics can be mapped to an NHH governing a spatial network of coupled resonators with high-order EPs.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Recently, there has been intense research in proposing and developing various methods for constructing high-order exceptional points (EPs) in dissipative systems. These EPs can possess a number of intriguing properties related to, e.g., chiral transport and enhanced sensitivity. Previous proposals to realize non-Hermitian Hamiltonians (NHHs) with high-order EPs have been mainly based on either direct construction of spatial networks of coupled modes or utilization of synthetic dimensions, e.g., mapping of spatial lattices to time or photon-number space. Both methods rely on the construction of effective NHHs describing classical or postselected quantum fields, which neglect the effects of quantum jumps and which, thus, suffer from a scalability problem in the quantum regime, when the probability of quantum jumps increases with the number of excitations and dissipation rate. Here, by considering the full quantum dynamics of a quadratic Liouvillian superoperator, we introduce a simple and effective method for engineering NHHs with high-order quantum EPs, derived from evolution matrices of system operator moments. That is, by quantizing higher-order moments of system operators, e.g., of a quadratic two-mode system, the resulting evolution matrices can be interpreted as alternative NHHs describing, e.g., a spatial lattice of coupled resonators, where spatial sites are represented by high-order field moments in the synthetic space of field moments. Notably, such a mapping allows correct reproduction of the results of the Liouvillian dynamics, including quantum jumps. As an example, we consider a U(1)-symmetric quadratic Liouvillian describing a bimodal cavity with incoherent mode coupling, which can also possess anti−PT symmetry, whose field moment dynamics can be mapped to an NHH governing a spatial network of coupled resonators with high-order EPs. |
| 24. | T F Gundogdu, M Gokkavas, Andriy E. Serebryannikov, E Ozbay Evidence of asymmetric beaming in a piecewise-linear propagation channel Opt. Lett., 46 (12), pp. 2928–2931, 2021. @article{Gundogdu:21, title = {Evidence of asymmetric beaming in a piecewise-linear propagation channel}, author = {T F Gundogdu and M Gokkavas and Andriy E. Serebryannikov and E Ozbay}, url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-46-12-2928}, doi = {10.1364/OL.420297}, year = {2021}, date = {2021-06-14}, journal = {Opt. Lett.}, volume = {46}, number = {12}, pages = {2928--2931}, publisher = {Optica Publishing Group}, abstract = {Asymmetric beaming in a piecewise-linear propagation channel is demonstrated for a single photonic-crystal prism at Gaussian-beam illumination. The used hybrid refraction--diffraction mechanism exploits oblique incidence, the first-negative-order deflection at the longer interface, and asymmetry in coupling at the exit interfaces and does not need blocking of transmission by dispersion in the backward illumination case. The Floquet--Bloch mode with left-handed behavior and nearly circular equifrequency dispersion contours is utilized. The outgoing waves may have significantly different spatial distributions for the forward and backward illumination cases, yielding asymmetry in the beaming regime.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Asymmetric beaming in a piecewise-linear propagation channel is demonstrated for a single photonic-crystal prism at Gaussian-beam illumination. The used hybrid refraction--diffraction mechanism exploits oblique incidence, the first-negative-order deflection at the longer interface, and asymmetry in coupling at the exit interfaces and does not need blocking of transmission by dispersion in the backward illumination case. The Floquet--Bloch mode with left-handed behavior and nearly circular equifrequency dispersion contours is utilized. The outgoing waves may have significantly different spatial distributions for the forward and backward illumination cases, yielding asymmetry in the beaming regime. |
| 23. | Felix Groß, Mateusz Zelent, Ajay Gangwar, Sławomir Mamica, Paweł Gruszecki, Matthias Werner, Gisela Schütz, Markus Weigand, Eberhard J Goering, Christian H Back, Maciej Krawczyk, Joachim Gräfe Phase resolved observation of spin wave modes in antidot lattices Appl. Phys. Lett., 118 (23), pp. 232403, 2021. @article{doi:10.1063/5.0045142, title = {Phase resolved observation of spin wave modes in antidot lattices}, author = {Felix Groß and Mateusz Zelent and Ajay Gangwar and Sławomir Mamica and Paweł Gruszecki and Matthias Werner and Gisela Schütz and Markus Weigand and Eberhard J Goering and Christian H Back and Maciej Krawczyk and Joachim Gräfe}, url = {https://doi.org/10.1063/5.0045142}, doi = {10.1063/5.0045142}, year = {2021}, date = {2021-06-10}, journal = {Appl. Phys. Lett.}, volume = {118}, number = {23}, pages = {232403}, abstract = {Antidot lattices have proven to be a powerful tool for spin wave band structure manipulation. Utilizing time-resolved scanning transmission x-ray microscopy, we are able to experimentally image edge-localized spin wave modes in an antidot lattice with a lateral confinement down to <80nm x 130 nm. At higher frequencies, spin wave dragonfly patterns formed by the demagnetizing structures of the antidot lattice are excited. Evaluating their relative phase with respect to the propagating mode within the antidot channel reveals that the dragonfly modes are not directly excited by the antenna but need the propagating mode as an energy mediator. Furthermore, micromagnetic simulations reveal that additional dispersion branches exist for a tilted external field geometry. These branches correspond to asymmetric spin wave modes that cannot be excited in a non-tilted field geometry due to the symmetry restriction. In addition to the band having a negative slope, these asymmetric modes also cause an unexpected transformation of the band structure, slightly reaching into the otherwise empty bandgap between the low frequency edge modes and the fundamental mode. The presented phase resolved investigation of spin waves is a crucial step for spin wave manipulation in magnonic crystals.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Antidot lattices have proven to be a powerful tool for spin wave band structure manipulation. Utilizing time-resolved scanning transmission x-ray microscopy, we are able to experimentally image edge-localized spin wave modes in an antidot lattice with a lateral confinement down to <80nm x 130 nm. At higher frequencies, spin wave dragonfly patterns formed by the demagnetizing structures of the antidot lattice are excited. Evaluating their relative phase with respect to the propagating mode within the antidot channel reveals that the dragonfly modes are not directly excited by the antenna but need the propagating mode as an energy mediator. Furthermore, micromagnetic simulations reveal that additional dispersion branches exist for a tilted external field geometry. These branches correspond to asymmetric spin wave modes that cannot be excited in a non-tilted field geometry due to the symmetry restriction. In addition to the band having a negative slope, these asymmetric modes also cause an unexpected transformation of the band structure, slightly reaching into the otherwise empty bandgap between the low frequency edge modes and the fundamental mode. The presented phase resolved investigation of spin waves is a crucial step for spin wave manipulation in magnonic crystals. |