Publications by Department of Quantum Information
Departments of ISQI | Publications of ISQI
2024 |
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| 67. | Jan Roik, Karol Bartkiewicz, Antonín Černoch, Karel Lemr Routing in quantum communication networks using reinforcement machine learning Quantum Information Processing, 23 (3), 2024, ISSN: 1573-1332. @article{Roik2024, title = {Routing in quantum communication networks using reinforcement machine learning}, author = {Jan Roik and Karol Bartkiewicz and Antonín Černoch and Karel Lemr}, url = {http://dx.doi.org/10.1007/s11128-024-04287-z}, doi = {10.1007/s11128-024-04287-z}, issn = {1573-1332}, year = {2024}, date = {2024-01-01}, journal = {Quantum Information Processing}, volume = {23}, number = {3}, publisher = {Springer Science and Business Media LLC}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 66. | Joanna K Kalaga, Anna Kowalewska-Kudłaszyk, Wiesław Leoński, Jan Peřina Legget-Garg inequality for a two-mode entangled bosonic system Optics Express, 32 (6), pp. 9946, 2024, ISSN: 1094-4087. @article{Kalaga2024, title = {Legget-Garg inequality for a two-mode entangled bosonic system}, author = {Joanna K Kalaga and Anna Kowalewska-Kudłaszyk and Wiesław Leoński and Jan Peřina}, url = {http://dx.doi.org/10.1364/OE.513855}, doi = {10.1364/oe.513855}, issn = {1094-4087}, year = {2024}, date = {2024-01-01}, journal = {Optics Express}, volume = {32}, number = {6}, pages = {9946}, publisher = {Optica Publishing Group}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 65. | Seungbeom Chin, Yong-Su Kim, Marcin Karczewski Shortcut to multipartite entanglement generation: A graph approach to boson subtractions npj Quantum Information, 10 (1), 2024, ISSN: 2056-6387. @article{Chin2024, title = {Shortcut to multipartite entanglement generation: A graph approach to boson subtractions}, author = {Seungbeom Chin and Yong-Su Kim and Marcin Karczewski}, url = {http://dx.doi.org/10.1038/s41534-024-00845-6}, doi = {10.1038/s41534-024-00845-6}, issn = {2056-6387}, year = {2024}, date = {2024-01-01}, journal = {npj Quantum Information}, volume = {10}, number = {1}, publisher = {Springer Science and Business Media LLC}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 64. | Seungbeom Chin, Marcin Karczewski, Yong-Su Kim Heralded Optical Entanglement Generation via the Graph Picture of Linear Quantum Networks Quantum, 8 , pp. 1572, 2024, ISSN: 2521-327X. @article{Chin2024heraldedoptical, title = {Heralded Optical Entanglement Generation via the Graph Picture of Linear Quantum Networks}, author = {Seungbeom Chin and Marcin Karczewski and Yong-Su Kim}, url = {https://doi.org/10.22331/q-2024-12-18-1572}, doi = {10.22331/q-2024-12-18-1572}, issn = {2521-327X}, year = {2024}, date = {2024-01-01}, journal = {Quantum}, volume = {8}, pages = {1572}, publisher = {Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 63. | Jolanta Natalia Latosińska, Magdalena Latosińska, Janez Seliger, Veselko Žagar, Tomaž Apih Pharmaceuticals, 17 (4), 2024, ISSN: 1424-8247. @article{ph17040445, title = {Butterfly Effect in Cytarabine: Combined NMR-NQR Experiment, Solid-State Computational Modeling, Quantitative Structure-Property Relationships and Molecular Docking Study}, author = {Jolanta Natalia Latosińska and Magdalena Latosińska and Janez Seliger and Veselko Žagar and Tomaž Apih}, url = {https://www.mdpi.com/1424-8247/17/4/445}, doi = {10.3390/ph17040445}, issn = {1424-8247}, year = {2024}, date = {2024-01-01}, journal = {Pharmaceuticals}, volume = {17}, number = {4}, abstract = {Cytarabine (Ara-C) is a synthetic isomer of cytidine that differs from cytidine and deoxycytidine only in the sugar. The use of arabinose instead of deoxyribose hinders the formation of phosphodiester linkages between pentoses, preventing the DNA chain from elongation and interrupting the DNA synthesis. The minor structural alteration (the inversion of hydroxyl at the 2′ positions of the sugar) leads to change of the biological activity from anti-depressant and DNA/RNA block builder to powerful anti-cancer. Our study aimed to determine the molecular nature of this phenomenon. Three 1H-14N NMR-NQR experimental techniques, followed by solid-state computational modelling (Quantum Theory of Atoms in Molecules, Reduced Density Gradient and 3D Hirshfeld surfaces), Quantitative Structure–Property Relationships, Spackman’s Hirshfeld surfaces and Molecular Docking were used. Multifaceted analysis—combining experiments, computational modeling and molecular docking—provides deep insight into three-dimensional packing at the atomic and molecular levels, but is challenging. A spectrum with nine lines indicating the existence of three chemically inequivalent nitrogen sites in the Ara-C molecule was recorded, and the lines were assigned to them. The influence of the structural alteration on the NQR parameters was modeled in the solid (GGA/RPBE). For the comprehensive description of the nature of these interactions several factors were considered, including relative reactivity and the involvement of heavy atoms in various non-covalent interactions. The binding modes in the solid state and complex with dCK were investigated using the novel approaches: radial plots, heatmaps and root-mean-square deviation of the binding mode. We identified the intramolecular OH···O hydrogen bond as the key factor responsible for forcing the glycone conformation and strengthening NH···O bonds with Gln97, Asp133 and Ara128, and stacking with Phe137. The titular butterfly effect is associated with both the inversion and the presence of this intramolecular hydrogen bond. Our study elucidates the differences in the binding modes of Ara-C and cytidine, which should guide the design of more potent anti-cancer and anti-viral analogues.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Cytarabine (Ara-C) is a synthetic isomer of cytidine that differs from cytidine and deoxycytidine only in the sugar. The use of arabinose instead of deoxyribose hinders the formation of phosphodiester linkages between pentoses, preventing the DNA chain from elongation and interrupting the DNA synthesis. The minor structural alteration (the inversion of hydroxyl at the 2′ positions of the sugar) leads to change of the biological activity from anti-depressant and DNA/RNA block builder to powerful anti-cancer. Our study aimed to determine the molecular nature of this phenomenon. Three 1H-14N NMR-NQR experimental techniques, followed by solid-state computational modelling (Quantum Theory of Atoms in Molecules, Reduced Density Gradient and 3D Hirshfeld surfaces), Quantitative Structure–Property Relationships, Spackman’s Hirshfeld surfaces and Molecular Docking were used. Multifaceted analysis—combining experiments, computational modeling and molecular docking—provides deep insight into three-dimensional packing at the atomic and molecular levels, but is challenging. A spectrum with nine lines indicating the existence of three chemically inequivalent nitrogen sites in the Ara-C molecule was recorded, and the lines were assigned to them. The influence of the structural alteration on the NQR parameters was modeled in the solid (GGA/RPBE). For the comprehensive description of the nature of these interactions several factors were considered, including relative reactivity and the involvement of heavy atoms in various non-covalent interactions. The binding modes in the solid state and complex with dCK were investigated using the novel approaches: radial plots, heatmaps and root-mean-square deviation of the binding mode. We identified the intramolecular OH···O hydrogen bond as the key factor responsible for forcing the glycone conformation and strengthening NH···O bonds with Gln97, Asp133 and Ara128, and stacking with Phe137. The titular butterfly effect is associated with both the inversion and the presence of this intramolecular hydrogen bond. Our study elucidates the differences in the binding modes of Ara-C and cytidine, which should guide the design of more potent anti-cancer and anti-viral analogues. |
| 62. | Magdalena Latosińska, Jolanta Natalia Latosińska Molecules, 29 (2), pp. 441, 2024, ISSN: 1420-3049. @article{Latosiska2024, title = {Favipiravir Analogues as Inhibitors of SARS-CoV-2 RNA-Dependent RNA Polymerase, Combined Quantum Chemical Modeling, Quantitative Structure–Property Relationship, and Molecular Docking Study}, author = {Magdalena Latosińska and Jolanta Natalia Latosińska}, url = {http://dx.doi.org/10.3390/molecules29020441}, doi = {10.3390/molecules29020441}, issn = {1420-3049}, year = {2024}, date = {2024-01-01}, journal = {Molecules}, volume = {29}, number = {2}, pages = {441}, publisher = {MDPI AG}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 61. | E S Hevorkian, V P Nerubatskyi, R V Vovk, T Szumiata, Jolanta Natalia Latosińska Foamy ceramic filters and new possibilities of their applications Ceramics International, 50 (4), pp. 6961–6968, 2024, ISSN: 0272-8842. @article{Hevorkian2024b, title = {Foamy ceramic filters and new possibilities of their applications}, author = {E S Hevorkian and V P Nerubatskyi and R V Vovk and T Szumiata and Jolanta Natalia Latosińska}, url = {http://dx.doi.org/10.1016/j.ceramint.2023.12.046}, doi = {10.1016/j.ceramint.2023.12.046}, issn = {0272-8842}, year = {2024}, date = {2024-01-01}, journal = {Ceramics International}, volume = {50}, number = {4}, pages = {6961–6968}, publisher = {Elsevier BV}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 60. | Magdalena Latosińska, Jolanta Natalia Latosińska Molecules, 29 (13), 2024, ISSN: 1420-3049. @article{molecules29133199, title = {Serine/Threonine Protein Kinases as Attractive Targets for Anti-Cancer Drugs—An Innovative Approach to Ligand Tuning Using Combined Quantum Chemical Calculations, Molecular Docking, Molecular Dynamic Simulations, and Network-like Similarity Graphs}, author = {Magdalena Latosińska and Jolanta Natalia Latosińska}, url = {https://www.mdpi.com/1420-3049/29/13/3199}, doi = {10.3390/molecules29133199}, issn = {1420-3049}, year = {2024}, date = {2024-01-01}, journal = {Molecules}, volume = {29}, number = {13}, abstract = {Serine/threonine protein kinases (CK2, PIM-1, RIO1) are constitutively active, highly conserved, pleiotropic, and multifunctional kinases, which control several signaling pathways and regulate many cellular functions, such as cell activity, survival, proliferation, and apoptosis. Over the past decades, they have gained increasing attention as potential therapeutic targets, ranging from various cancers and neurological, inflammation, and autoimmune disorders to viral diseases, including COVID-19. Despite the accumulation of a vast amount of experimental data, there is still no “recipe” that would facilitate the search for new effective kinase inhibitors. The aim of our study was to develop an effective screening method that would be useful for this purpose. A combination of Density Functional Theory calculations and molecular docking, supplemented with newly developed quantitative methods for the comparison of the binding modes, provided deep insight into the set of desirable properties responsible for their inhibition. The mathematical metrics helped assess the distance between the binding modes, while heatmaps revealed the locations in the ligand that should be modified according to binding site requirements. The Structure-Binding Affinity Index and Structural-Binding Affinity Landscape proposed in this paper helped to measure the extent to which binding affinity is gained or lost in response to a relatively small change in the ligand’s structure. The combination of the physico-chemical profile with the aforementioned factors enabled the identification of both “dead” and “promising” search directions. Tests carried out on experimental data have validated and demonstrated the high efficiency of the proposed innovative approach. Our method for quantifying differences between the ligands and their binding capabilities holds promise for guiding future research on new anti-cancer agents.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Serine/threonine protein kinases (CK2, PIM-1, RIO1) are constitutively active, highly conserved, pleiotropic, and multifunctional kinases, which control several signaling pathways and regulate many cellular functions, such as cell activity, survival, proliferation, and apoptosis. Over the past decades, they have gained increasing attention as potential therapeutic targets, ranging from various cancers and neurological, inflammation, and autoimmune disorders to viral diseases, including COVID-19. Despite the accumulation of a vast amount of experimental data, there is still no “recipe” that would facilitate the search for new effective kinase inhibitors. The aim of our study was to develop an effective screening method that would be useful for this purpose. A combination of Density Functional Theory calculations and molecular docking, supplemented with newly developed quantitative methods for the comparison of the binding modes, provided deep insight into the set of desirable properties responsible for their inhibition. The mathematical metrics helped assess the distance between the binding modes, while heatmaps revealed the locations in the ligand that should be modified according to binding site requirements. The Structure-Binding Affinity Index and Structural-Binding Affinity Landscape proposed in this paper helped to measure the extent to which binding affinity is gained or lost in response to a relatively small change in the ligand’s structure. The combination of the physico-chemical profile with the aforementioned factors enabled the identification of both “dead” and “promising” search directions. Tests carried out on experimental data have validated and demonstrated the high efficiency of the proposed innovative approach. Our method for quantifying differences between the ligands and their binding capabilities holds promise for guiding future research on new anti-cancer agents. |
| 59. | Edvin Hevorkian, Remigiusz Michalczewski, Miroslaw Rucki, Dmitry Sofronov, Edyta Osuch-Słomka, Volodymyr Nerubatskyi, Zbigniew Krzysiak, Jolanta Natalia Latosińska Ceramics International, 50 (19, Part A), pp. 35226-35235, 2024, ISSN: 0272-8842. @article{HEVORKIAN202435226, title = {Effect of the sintering parameters on the structure and mechanical properties of zirconia-based ceramics}, author = {Edvin Hevorkian and Remigiusz Michalczewski and Miroslaw Rucki and Dmitry Sofronov and Edyta Osuch-Słomka and Volodymyr Nerubatskyi and Zbigniew Krzysiak and Jolanta Natalia Latosińska}, url = {https://www.sciencedirect.com/science/article/pii/S0272884224027688}, doi = {https://doi.org/10.1016/j.ceramint.2024.06.331}, issn = {0272-8842}, year = {2024}, date = {2024-01-01}, journal = {Ceramics International}, volume = {50}, number = {19, Part A}, pages = {35226-35235}, abstract = {The paper presents the results of an investigations of the sintered zirconia ceramics that have been stabilized with Y2O3 and CeO2. The initial powders were synthesized via decomposition of the fluoride salts, which determined morphological features and dimensions of the particles. The specific electroconsolidation process, performed using the modified spark plasma sintering device, allowed for the retention of the nanoscale grain sizes and related properties of the sintered ceramic composites. It was found that the as-obtained materials with cerium oxide exhibited high bending strength of 609 MPa, by ca. 33 % higher than that of yttria-stabilized ones (410 MPa). In turn, the best combination of hardness and fracture toughness, K1С = 5.8 МPа·m1/2 аnd Нv = 14.8 GPа, respectively, exhibited ZrO2+3 wt% Y2O3. This result can be attributed to the chemical composition and morphology of the powders, which in turn is influenced by the synthesis conditions and calcination time and temperatures, as well as to the sintering parameters. In particular, yttria-stabilized zirconia showed higher sensitivity to the variations of the sintering temperatures and holding times.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The paper presents the results of an investigations of the sintered zirconia ceramics that have been stabilized with Y2O3 and CeO2. The initial powders were synthesized via decomposition of the fluoride salts, which determined morphological features and dimensions of the particles. The specific electroconsolidation process, performed using the modified spark plasma sintering device, allowed for the retention of the nanoscale grain sizes and related properties of the sintered ceramic composites. It was found that the as-obtained materials with cerium oxide exhibited high bending strength of 609 MPa, by ca. 33 % higher than that of yttria-stabilized ones (410 MPa). In turn, the best combination of hardness and fracture toughness, K1С = 5.8 МPа·m1/2 аnd Нv = 14.8 GPа, respectively, exhibited ZrO2+3 wt% Y2O3. This result can be attributed to the chemical composition and morphology of the powders, which in turn is influenced by the synthesis conditions and calcination time and temperatures, as well as to the sintering parameters. In particular, yttria-stabilized zirconia showed higher sensitivity to the variations of the sintering temperatures and holding times. |
| 58. | Magdalena Latosińska, Jolanta Natalia Latosińska Viruses, 16 (7), 2024, ISSN: 1999-4915. @article{v16071073, title = {The Chameleon Strategy—A Recipe for Effective Ligand Screening for Viral Targets Based on Four Novel Structure–Binding Strength Indices}, author = {Magdalena Latosińska and Jolanta Natalia Latosińska}, url = {https://www.mdpi.com/1999-4915/16/7/1073}, doi = {10.3390/v16071073}, issn = {1999-4915}, year = {2024}, date = {2024-01-01}, journal = {Viruses}, volume = {16}, number = {7}, abstract = {The RNA viruses SARS-CoV, SARS-CoV-2 and MERS-CoV encode the non-structural Nsp16 (2′-O-methyltransferase) that catalyzes the transfer of a methyl group from S-adenosylmethionine (SAM) to the first ribonucleotide in mRNA. Recently, it has been found that breaking the bond between Nsp16 and SAM substrate results in the cessation of mRNA virus replication. To date, only a limited number of such inhibitors have been identified, which can be attributed to a lack of an effective “recipe”. The aim of our study was to propose and verify a rapid and effective screening protocol dedicated to such purposes. We proposed four new indices describing structure-binding strength (structure–binding affinity, structure–hydrogen bonding, structure–steric and structure–protein–ligand indices) were then applied and shown to be extremely helpful in determining the degree of increase or decrease in binding affinity in response to a relatively small change in the ligand structure. After initial pre-selection, based on similarity to SAM, we limited the study to 967 compounds, so-called molecular chameleons. They were then docked in the Nsp16 protein pocket, and 10 candidate ligands were selected using the novel structure-binding affinity index. Subsequently the selected 10 candidate ligands and 8 known inhibitors and were docked to Nsp16 pockets from SARS-CoV-2, MERS-CoV and SARS-CoV. Based on the four new indices, the best ligands were selected and a new one was designed by tuning them. Finally, ADMET profiling and molecular dynamics simulations were performed for the best ligands. The new structure-binding strength indices can be successfully applied not only to screen and tune ligands, but also to determine the effectiveness of the ligand in response to changes in the target viral entity, which is particularly useful for assessing drug effectiveness in the case of alterations in viral proteins. The developed approach, the so-called chameleon strategy, has the capacity to introduce a novel universal paradigm to the field of drugs design, including RNA antivirals.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The RNA viruses SARS-CoV, SARS-CoV-2 and MERS-CoV encode the non-structural Nsp16 (2′-O-methyltransferase) that catalyzes the transfer of a methyl group from S-adenosylmethionine (SAM) to the first ribonucleotide in mRNA. Recently, it has been found that breaking the bond between Nsp16 and SAM substrate results in the cessation of mRNA virus replication. To date, only a limited number of such inhibitors have been identified, which can be attributed to a lack of an effective “recipe”. The aim of our study was to propose and verify a rapid and effective screening protocol dedicated to such purposes. We proposed four new indices describing structure-binding strength (structure–binding affinity, structure–hydrogen bonding, structure–steric and structure–protein–ligand indices) were then applied and shown to be extremely helpful in determining the degree of increase or decrease in binding affinity in response to a relatively small change in the ligand structure. After initial pre-selection, based on similarity to SAM, we limited the study to 967 compounds, so-called molecular chameleons. They were then docked in the Nsp16 protein pocket, and 10 candidate ligands were selected using the novel structure-binding affinity index. Subsequently the selected 10 candidate ligands and 8 known inhibitors and were docked to Nsp16 pockets from SARS-CoV-2, MERS-CoV and SARS-CoV. Based on the four new indices, the best ligands were selected and a new one was designed by tuning them. Finally, ADMET profiling and molecular dynamics simulations were performed for the best ligands. The new structure-binding strength indices can be successfully applied not only to screen and tune ligands, but also to determine the effectiveness of the ligand in response to changes in the target viral entity, which is particularly useful for assessing drug effectiveness in the case of alterations in viral proteins. The developed approach, the so-called chameleon strategy, has the capacity to introduce a novel universal paradigm to the field of drugs design, including RNA antivirals. |
| 57. | Jan Wójcik Quantum walks in weak stochastic gauge fields Physics Letters A, 512 , pp. 129605, 2024, ISSN: 0375-9601. @article{WOJCIK2024129605, title = {Quantum walks in weak stochastic gauge fields}, author = {Jan Wójcik}, url = {https://www.sciencedirect.com/science/article/pii/S0375960124002998}, doi = {https://doi.org/10.1016/j.physleta.2024.129605}, issn = {0375-9601}, year = {2024}, date = {2024-01-01}, journal = {Physics Letters A}, volume = {512}, pages = {129605}, abstract = {Contrary to the ballistic dynamics of standard quantum walks, the behavior of stochastic quantum walks is known to be diffusive. Here we study discrete time quantum walks in weak stochastic gauge fields. In the case of position and spin dependent gauge field, we observe a transition from ballistic to diffusive motion, with the probability distribution becoming Gaussian. However, in contradiction to common belief, weak stochastic electric gauge fields reveal the persistence of Bloch oscillations despite decoherence which we demonstrate on simulations and prove analytically. The proposed models provide insights into the interplay between randomness and coherent dynamics of quantum walks.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Contrary to the ballistic dynamics of standard quantum walks, the behavior of stochastic quantum walks is known to be diffusive. Here we study discrete time quantum walks in weak stochastic gauge fields. In the case of position and spin dependent gauge field, we observe a transition from ballistic to diffusive motion, with the probability distribution becoming Gaussian. However, in contradiction to common belief, weak stochastic electric gauge fields reveal the persistence of Bloch oscillations despite decoherence which we demonstrate on simulations and prove analytically. The proposed models provide insights into the interplay between randomness and coherent dynamics of quantum walks. |
2023 |
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| 56. | Andrzej Grudka, Paweł Kurzyński, Adam S Sajna, Jan Wójcik, Antoni Wójcik Exposing hypersensitivity in quantum chaotic dynamics Phys. Rev. E, 108 , pp. 064212, 2023. @article{PhysRevE.108.064212, title = {Exposing hypersensitivity in quantum chaotic dynamics}, author = {Andrzej Grudka and Paweł Kurzyński and Adam S Sajna and Jan Wójcik and Antoni Wójcik}, url = {https://link.aps.org/doi/10.1103/PhysRevE.108.064212}, doi = {10.1103/PhysRevE.108.064212}, year = {2023}, date = {2023-12-01}, journal = {Phys. Rev. E}, volume = {108}, pages = {064212}, publisher = {American Physical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 55. | Javid Naikoo, Ravindra W. Chhajlany, Jan Kołodyński Multiparameter Estimation Perspective on Non-Hermitian Singularity-Enhanced Sensing Phys. Rev. Lett., 131 , pp. 220801, 2023. @article{PhysRevLett.131.220801, title = {Multiparameter Estimation Perspective on Non-Hermitian Singularity-Enhanced Sensing}, author = {Javid Naikoo and Ravindra W. Chhajlany and Jan Kołodyński}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.131.220801}, doi = {10.1103/PhysRevLett.131.220801}, year = {2023}, date = {2023-11-29}, journal = {Phys. Rev. Lett.}, volume = {131}, pages = {220801}, publisher = {American Physical Society}, abstract = {Describing the evolution of quantum systems by means of non-Hermitian generators opens a new avenue to explore the dynamical properties naturally emerging in such a picture, e.g. operation at the so-called exceptional points, preservation of parity-time symmetry, or capitalizing on the singular behavior of the dynamics. In this Letter, we focus on the possibility of achieving unbounded sensitivity when using the system to sense linear perturbations away from a singular point. By combining multiparameter estimation theory of Gaussian quantum systems with the one of singular-matrix perturbations, we introduce the necessary tools to study the ultimate limits on the precision attained by such singularity-tuned sensors. We identify under what conditions and at what rate can the resulting sensitivity indeed diverge, in order to show that nuisance parameters should be generally included in the analysis, as their presence may alter the scaling of the error with the estimated parameter.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Describing the evolution of quantum systems by means of non-Hermitian generators opens a new avenue to explore the dynamical properties naturally emerging in such a picture, e.g. operation at the so-called exceptional points, preservation of parity-time symmetry, or capitalizing on the singular behavior of the dynamics. In this Letter, we focus on the possibility of achieving unbounded sensitivity when using the system to sense linear perturbations away from a singular point. By combining multiparameter estimation theory of Gaussian quantum systems with the one of singular-matrix perturbations, we introduce the necessary tools to study the ultimate limits on the precision attained by such singularity-tuned sensors. We identify under what conditions and at what rate can the resulting sensitivity indeed diverge, in order to show that nuisance parameters should be generally included in the analysis, as their presence may alter the scaling of the error with the estimated parameter. |
| 54. | Andrzej Grudka, Jȩdrzej Stempin, Jan Wójcik, Antoni Wójcik Superluminal observers do not explain quantum superpositions Physics Letters A, 487 , pp. 129127, 2023. @article{Grudka2023, title = {Superluminal observers do not explain quantum superpositions}, author = {Andrzej Grudka and Jȩdrzej Stempin and Jan Wójcik and Antoni Wójcik}, url = {https://www.sciencedirect.com/science/article/pii/S0375960123005078}, doi = {10.1016/j.physleta.2023.129127}, year = {2023}, date = {2023-11-05}, journal = {Physics Letters A}, volume = {487}, pages = {129127}, abstract = {The quantum description of reality is quite different from the classical one. Understanding this difference at a fundamental level is still an interesting topic. Recently, Dragan and Ekert (2020) postulated that considering so-called superluminal observers can be useful in this context. In particular, they claim that the full mathematical structure of the generalized Lorentz transformation may imply the emergence of multiple quantum mechanical trajectories. On the contrary, here we show that the generalized Lorentz transformation, when used in a consistent way, does not provide any correspondence between the classical concept of a definite path and the multiple paths of quantum mechanics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The quantum description of reality is quite different from the classical one. Understanding this difference at a fundamental level is still an interesting topic. Recently, Dragan and Ekert (2020) postulated that considering so-called superluminal observers can be useful in this context. In particular, they claim that the full mathematical structure of the generalized Lorentz transformation may imply the emergence of multiple quantum mechanical trajectories. On the contrary, here we show that the generalized Lorentz transformation, when used in a consistent way, does not provide any correspondence between the classical concept of a definite path and the multiple paths of quantum mechanics. |
| 53. | Ievgen I. Arkhipov, Adam Miranowicz, Franco Nori, Şahin K. Özdemir, Fabrizio Minganti Fully solvable finite simplex lattices with open boundaries in arbitrary dimensions Phys. Rev. Res., 5 , pp. 043092, 2023. @article{Arkhipov2023b, title = {Fully solvable finite simplex lattices with open boundaries in arbitrary dimensions}, author = {Ievgen I. Arkhipov and Adam Miranowicz and Franco Nori and Şahin K. Özdemir and Fabrizio Minganti}, url = {https://link.aps.org/doi/10.1103/PhysRevResearch.5.043092}, doi = {10.1103/PhysRevResearch.5.043092}, year = {2023}, date = {2023-10-26}, journal = {Phys. Rev. Res.}, volume = {5}, pages = {043092}, abstract = {Finite simplex lattice models are used in different branches of science, e.g., in condensed-matter physics, when studying frustrated magnetic systems and non-Hermitian localization phenomena; or in chemistry, when describing experiments with mixtures. An n-simplex represents the simplest possible polytope in n dimensions, e.g., a line segment, a triangle, and a tetrahedron in one, two, and three dimensions, respectively. In this work, we show that various fully solvable, in general non-Hermitian, n-simplex lattice models with open boundaries can be constructed from the high-order field-moments space of quadratic bosonic systems. Namely, we demonstrate that such n-simplex lattices can be formed by a dimensional reduction of highly degenerate iterated polytope chains in (k>n)-dimensions, which naturally emerge in the field-moments space. Our findings indicate that the field-moments space of bosonic systems provides a versatile platform for simulating real-space n-simplex lattices exhibiting non-Hermitian phenomena, and it yields valuable insights into the structure of many-body systems exhibiting similar complexity. Among a variety of practical applications, these simplex structures can offer a physical setting for implementing the discrete fractional Fourier transform, an indispensable tool for both quantum and classical signal processing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Finite simplex lattice models are used in different branches of science, e.g., in condensed-matter physics, when studying frustrated magnetic systems and non-Hermitian localization phenomena; or in chemistry, when describing experiments with mixtures. An n-simplex represents the simplest possible polytope in n dimensions, e.g., a line segment, a triangle, and a tetrahedron in one, two, and three dimensions, respectively. In this work, we show that various fully solvable, in general non-Hermitian, n-simplex lattice models with open boundaries can be constructed from the high-order field-moments space of quadratic bosonic systems. Namely, we demonstrate that such n-simplex lattices can be formed by a dimensional reduction of highly degenerate iterated polytope chains in (k>n)-dimensions, which naturally emerge in the field-moments space. Our findings indicate that the field-moments space of bosonic systems provides a versatile platform for simulating real-space n-simplex lattices exhibiting non-Hermitian phenomena, and it yields valuable insights into the structure of many-body systems exhibiting similar complexity. Among a variety of practical applications, these simplex structures can offer a physical setting for implementing the discrete fractional Fourier transform, an indispensable tool for both quantum and classical signal processing. |
| 52. | Jan Peřina, Jr., Adam Miranowicz, Joanna K. Kalaga, Wiesław Leoński Unavoidability of nonclassicality loss in PT-symmetric systems Phys. Rev. A, 108 , pp. 033512, 2023. @article{Peřina2023, title = {Unavoidability of nonclassicality loss in PT-symmetric systems}, author = {Jan Peřina, Jr. and Adam Miranowicz and Joanna K. Kalaga and Wiesław Leoński}, url = {https://journals.aps.org/pra/abstract/10.1103/PhysRevA.108.033512}, doi = {10.1103/PhysRevA.108.033512}, year = {2023}, date = {2023-09-15}, journal = {Phys. Rev. A}, volume = {108}, pages = {033512}, abstract = {We show that the loss of nonclassicality (including quantum entanglement) cannot be compensated by the (incoherent) amplification of PT-symmetric systems. We address this problem by manipulating the quantum fluctuating forces in the Heisenberg-Langevin approach. Specifically, we analyze the dynamics of two nonlinearly coupled oscillator modes in a PT-symmetric system. An analytical solution allows us to separate the contribution of reservoir fluctuations from the evolution of quantum statistical properties of the modes. In general, as reservoir fluctuations act constantly, the complete loss of nonclassicality and entanglement is observed for long times. To elucidate the role of reservoir fluctuations in a long-time evolution of nonclassicality and entanglement, we consider and compare the predictions from two alternative models in which no fatal long-time detrimental effects on the nonclassicality and entanglement are observed. This is so as, in the first semiclassical model, no reservoir fluctuations are considered at all. This, however, violates the fluctuation-dissipation theorem. The second, more elaborated, model obeys the fluctuation-dissipation relations as it partly involves reservoir fluctuations. However, to prevent the above long-time detrimental effects, the reservoir fluctuations have to be endowed with the nonphysical properties of a sink model. In both models, additional incorporation of the omitted reservoir fluctuations results in their physically consistent behavior. This behavior, however, predicts the gradual loss of the nonclassicality and entanglement. Thus the effects of reservoir fluctuations related to damping cannot be compensated by those related to amplification. This qualitatively differs from the influence of damping and amplification to a direct coherent dynamics of PT-symmetric systems in which their mutual interference results in a periodic behavior allowing for nonclassicality and entanglement at arbitrary times.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We show that the loss of nonclassicality (including quantum entanglement) cannot be compensated by the (incoherent) amplification of PT-symmetric systems. We address this problem by manipulating the quantum fluctuating forces in the Heisenberg-Langevin approach. Specifically, we analyze the dynamics of two nonlinearly coupled oscillator modes in a PT-symmetric system. An analytical solution allows us to separate the contribution of reservoir fluctuations from the evolution of quantum statistical properties of the modes. In general, as reservoir fluctuations act constantly, the complete loss of nonclassicality and entanglement is observed for long times. To elucidate the role of reservoir fluctuations in a long-time evolution of nonclassicality and entanglement, we consider and compare the predictions from two alternative models in which no fatal long-time detrimental effects on the nonclassicality and entanglement are observed. This is so as, in the first semiclassical model, no reservoir fluctuations are considered at all. This, however, violates the fluctuation-dissipation theorem. The second, more elaborated, model obeys the fluctuation-dissipation relations as it partly involves reservoir fluctuations. However, to prevent the above long-time detrimental effects, the reservoir fluctuations have to be endowed with the nonphysical properties of a sink model. In both models, additional incorporation of the omitted reservoir fluctuations results in their physically consistent behavior. This behavior, however, predicts the gradual loss of the nonclassicality and entanglement. Thus the effects of reservoir fluctuations related to damping cannot be compensated by those related to amplification. This qualitatively differs from the influence of damping and amplification to a direct coherent dynamics of PT-symmetric systems in which their mutual interference results in a periodic behavior allowing for nonclassicality and entanglement at arbitrary times. |
| 51. | Jolanta Natalia Latosińska, Magdalena Latosińska, Janez Seliger, Veselko Žagar Processes, 11 (9), 2023, ISSN: 2227-9717. @article{pr11092740, title = {Exploring Partial Structural Disorder in Anhydrous Paraxanthine through Combined Experiment, Solid-State Computational Modelling, and Molecular Docking}, author = {Jolanta Natalia Latosińska and Magdalena Latosińska and Janez Seliger and Veselko Žagar}, url = {https://www.mdpi.com/2227-9717/11/9/2740}, doi = {10.3390/pr11092740}, issn = {2227-9717}, year = {2023}, date = {2023-09-14}, journal = {Processes}, volume = {11}, number = {9}, abstract = {Paraxanthine (PX), a major metabolite of caffeine, a protective agent against Alzheimer’s and Parkinson’s disease, and a promising drug for the treatment of post-COVID 2019 anosmia and ageusia, has been studied in the solid state and protein–ligand complex. Partial disorder in PX, caused by the methyl group at the N(7) position, has been modelled and discussed. The relationship between the unusual structural disorder and the propensity to form a specific system of non-covalent bonds was analyzed. Three 1H-14N NMR-NQR (nuclear magnetic resonance–nuclear quadrupole resonance) experimental techniques were used, namely multiple frequency sweeps, Larmor frequency scanning, and the two-frequency irradiation, followed by solid-state computational modelling (density functional theory, supplemented by quantum theory of atoms in molecules, 3D Hirshfeld surfaces, and reduced density gradient), and molecular docking approaches. New quantitative methods for estimating changes in the global pattern of interactions under the influence of rotation of the methyl group in N(7) based on the Pompeiu–Hausdorff and Bhattacharayya metrics and the Wasserstein distance have been proposed and applied. A spectrum consisting of 12 lines, indicating the presence of 4 chemically inequivalent nitrogen sites in the PX molecule, was recorded, and the lines’ assignment to particular sites was made. The influence of the methyl rotation on the eigenvalues and eigenvectors of the electric field gradient tensor, NQR parameters, and resonance line positions was modelled in the solid (GGA/RPBE, m-GGA/RSCAN) and cluster (Minnesota M062X hybrid). Three factors have been found to determine structural disorder in PX: larger crystal voids near the methyl at N(7) than at N(1) (opening the path for the disorder), hyperconjugation strongly affecting the density distribution in the five-membered ring, and the involvement of the methyl group at N(7) in many non-covalent bonds that intercept (capture) subsequent jumping protons. The Pompeiu–Hausdorff and Bhattacharayya metrics and the Wasserstein distance confirmed the changes in the distribution and strength of non-covalent interactions throughout the molecule as a result of methyl rotation. This effect is clearly visible regardless of the type of metric, and its order of magnitude is consistent with the modulation effect of the NQR spectra (experimental and calculated). Through molecular docking, it was discovered that the PX moiety in protein–ligand complexes adopt the same methyl group conformation at N(7) as in the solid state. It was found that the cooperation–competition between the C-H⋯O hydrogen bonds and C-H⋯H-C dispersion interactions is the crucial factor that impedes methyl rotation and induces structural disorder, as well as being an important factor in the formation of the protein–ligand complexes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Paraxanthine (PX), a major metabolite of caffeine, a protective agent against Alzheimer’s and Parkinson’s disease, and a promising drug for the treatment of post-COVID 2019 anosmia and ageusia, has been studied in the solid state and protein–ligand complex. Partial disorder in PX, caused by the methyl group at the N(7) position, has been modelled and discussed. The relationship between the unusual structural disorder and the propensity to form a specific system of non-covalent bonds was analyzed. Three 1H-14N NMR-NQR (nuclear magnetic resonance–nuclear quadrupole resonance) experimental techniques were used, namely multiple frequency sweeps, Larmor frequency scanning, and the two-frequency irradiation, followed by solid-state computational modelling (density functional theory, supplemented by quantum theory of atoms in molecules, 3D Hirshfeld surfaces, and reduced density gradient), and molecular docking approaches. New quantitative methods for estimating changes in the global pattern of interactions under the influence of rotation of the methyl group in N(7) based on the Pompeiu–Hausdorff and Bhattacharayya metrics and the Wasserstein distance have been proposed and applied. A spectrum consisting of 12 lines, indicating the presence of 4 chemically inequivalent nitrogen sites in the PX molecule, was recorded, and the lines’ assignment to particular sites was made. The influence of the methyl rotation on the eigenvalues and eigenvectors of the electric field gradient tensor, NQR parameters, and resonance line positions was modelled in the solid (GGA/RPBE, m-GGA/RSCAN) and cluster (Minnesota M062X hybrid). Three factors have been found to determine structural disorder in PX: larger crystal voids near the methyl at N(7) than at N(1) (opening the path for the disorder), hyperconjugation strongly affecting the density distribution in the five-membered ring, and the involvement of the methyl group at N(7) in many non-covalent bonds that intercept (capture) subsequent jumping protons. The Pompeiu–Hausdorff and Bhattacharayya metrics and the Wasserstein distance confirmed the changes in the distribution and strength of non-covalent interactions throughout the molecule as a result of methyl rotation. This effect is clearly visible regardless of the type of metric, and its order of magnitude is consistent with the modulation effect of the NQR spectra (experimental and calculated). Through molecular docking, it was discovered that the PX moiety in protein–ligand complexes adopt the same methyl group conformation at N(7) as in the solid state. It was found that the cooperation–competition between the C-H⋯O hydrogen bonds and C-H⋯H-C dispersion interactions is the crucial factor that impedes methyl rotation and induces structural disorder, as well as being an important factor in the formation of the protein–ligand complexes. |
| 50. | Ri-Hua Zheng, Wen Ning, Ye-Hong Chen, Jia-Hao Lü, Li-Tuo Shen, Kai Xu, Yu-Ran Zhang, Da Xu, Hekang Li, Yan Xia, Fan Wu, Zhen-Biao Yang, Adam Miranowicz, Neill Lambert, Dongning Zheng, Heng Fan, Franco Nori, Shi-Biao Zheng Observation of a Superradiant Phase Transition with Emergent Cat States Phys. Rev. Lett., 131 , pp. 113601 , 2023. @article{Zheng2023, title = {Observation of a Superradiant Phase Transition with Emergent Cat States}, author = {Ri-Hua Zheng and Wen Ning and Ye-Hong Chen and Jia-Hao Lü and Li-Tuo Shen and Kai Xu and Yu-Ran Zhang and Da Xu and Hekang Li and Yan Xia and Fan Wu and Zhen-Biao Yang and Adam Miranowicz and Neill Lambert and Dongning Zheng and Heng Fan and Franco Nori and Shi-Biao Zheng}, url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.113601}, doi = {10.1103/PhysRevLett.131.113601}, year = {2023}, date = {2023-09-11}, journal = {Phys. Rev. Lett.}, volume = {131}, pages = {113601 }, abstract = {Superradiant phase transitions (SPTs) are important for understanding light-matter interactions at the quantum level, and play a central role in criticality-enhanced quantum sensing. So far, SPTs have been observed in driven-dissipative systems, but the emergent light fields did not show any nonclassical characteristic due to the presence of strong dissipation. Here we report an experimental demonstration of the SPT featuring the emergence of a highly nonclassical photonic field, realized with a resonator coupled to a superconducting qubit, implementing the quantum Rabi model. We fully characterize the light-matter state by Wigner matrix tomography. The measured matrix elements exhibit quantum interference intrinsic of a photonic mesoscopic superposition, and reveal light-matter entanglement.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Superradiant phase transitions (SPTs) are important for understanding light-matter interactions at the quantum level, and play a central role in criticality-enhanced quantum sensing. So far, SPTs have been observed in driven-dissipative systems, but the emergent light fields did not show any nonclassical characteristic due to the presence of strong dissipation. Here we report an experimental demonstration of the SPT featuring the emergence of a highly nonclassical photonic field, realized with a resonator coupled to a superconducting qubit, implementing the quantum Rabi model. We fully characterize the light-matter state by Wigner matrix tomography. The measured matrix elements exhibit quantum interference intrinsic of a photonic mesoscopic superposition, and reveal light-matter entanglement. |
| 49. | Karol Bartkiewicz, Patrycja Tulewicz, Jan Roik, Karel Lemr Synergic quantum generative machine learning Scientific Reports, 13 (1), pp. 12893, 2023, ISSN: 2045-2322. @article{bartkiewicz_synergic_2023, title = {Synergic quantum generative machine learning}, author = {Karol Bartkiewicz and Patrycja Tulewicz and Jan Roik and Karel Lemr}, url = {https://www.nature.com/articles/s41598-023-40137-1}, doi = {10.1038/s41598-023-40137-1}, issn = {2045-2322}, year = {2023}, date = {2023-08-09}, urldate = {2023-10-18}, journal = {Scientific Reports}, volume = {13}, number = {1}, pages = {12893}, abstract = {We introduce a new approach towards generative quantum machine learning significantly reducing the number of hyperparameters and report on a proof-of-principle experiment demonstrating our approach. Our proposal depends on collaboration between the generators and discriminator, thus, we call it quantum synergic generative learning. We present numerical evidence that the synergic approach, in some cases, compares favorably to recently proposed quantum generative adversarial learning. In addition to the results obtained with quantum simulators, we also present experimental results obtained with an actual programmable quantum computer. We investigate how a quantum computer implementing generative learning algorithm could learn the concept of a maximally-entangled state. After completing the learning process, the network is able both to recognize and to generate an entangled state. Our approach can be treated as one possible preliminary step to understanding how the concept of quantum entanglement can be learned and demonstrated by a quantum computer.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We introduce a new approach towards generative quantum machine learning significantly reducing the number of hyperparameters and report on a proof-of-principle experiment demonstrating our approach. Our proposal depends on collaboration between the generators and discriminator, thus, we call it quantum synergic generative learning. We present numerical evidence that the synergic approach, in some cases, compares favorably to recently proposed quantum generative adversarial learning. In addition to the results obtained with quantum simulators, we also present experimental results obtained with an actual programmable quantum computer. We investigate how a quantum computer implementing generative learning algorithm could learn the concept of a maximally-entangled state. After completing the learning process, the network is able both to recognize and to generate an entangled state. Our approach can be treated as one possible preliminary step to understanding how the concept of quantum entanglement can be learned and demonstrated by a quantum computer. |
| 48. | Andrzej Grudka, Paweł Kurzyński, Tomasz P Polak, Adam S Sajna, Jan Wójcik, Antoni Wójcik Complementarity in quantum walks Journal of Physics A, 56 , pp. 275303, 2023. @article{grudka23-2, title = {Complementarity in quantum walks}, author = {Andrzej Grudka and Paweł Kurzyński and Tomasz P Polak and Adam S Sajna and Jan Wójcik and Antoni Wójcik}, doi = {10.1088/1751-8121/acdcd0}, year = {2023}, date = {2023-06-19}, journal = {Journal of Physics A}, volume = {56}, pages = {275303}, abstract = {The eigenbases of two quantum observables, {|ai⟩}Di=1 and {|bj⟩}Dj=1, form mutually unbiased bases (MUB) if |⟨ai |bj⟩| = 1/ √D for all i and j. In realistic situations MUB are hard to obtain and one looks for approximate MUB (AMUB), in which case the corresponding eigenbases obey |⟨ai |bj⟩| ⩽ c/√D, where c is some positive constant independent of D. In majority of cases observables corresponding to MUB and AMUB do not have clear physical interpretation. Here we study discrete-time quantum walks (QWs) on d-cycles with a position and coin-dependent phase-shift. Such a model simulates a dynamics of a quantum particle moving on a ring with an artificial gauge field. In our case the amplitude of the phase-shift is governed by a single discrete parameter q. We solve the model analytically and observe that for prime d the eigenvectors of two QW evolution operators form AMUB. Namely, if d is prime the corresponding eigenvectors of the evolution operators, that act in the D-dimensional Hilbert space (D = 2d), obey |⟨vq|v ′q ′ ⟩| ⩽√2/√D for q ̸= q ′ and for all |vq⟩ and |v ′q ′ ⟩. Finally, we show that the analogous AMUB relation still holds in the continuous version of this model, which corresponds to a one-dimensional Dirac particle.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The eigenbases of two quantum observables, {|ai⟩}Di=1 and {|bj⟩}Dj=1, form mutually unbiased bases (MUB) if |⟨ai |bj⟩| = 1/ √D for all i and j. In realistic situations MUB are hard to obtain and one looks for approximate MUB (AMUB), in which case the corresponding eigenbases obey |⟨ai |bj⟩| ⩽ c/√D, where c is some positive constant independent of D. In majority of cases observables corresponding to MUB and AMUB do not have clear physical interpretation. Here we study discrete-time quantum walks (QWs) on d-cycles with a position and coin-dependent phase-shift. Such a model simulates a dynamics of a quantum particle moving on a ring with an artificial gauge field. In our case the amplitude of the phase-shift is governed by a single discrete parameter q. We solve the model analytically and observe that for prime d the eigenvectors of two QW evolution operators form AMUB. Namely, if d is prime the corresponding eigenvectors of the evolution operators, that act in the D-dimensional Hilbert space (D = 2d), obey |⟨vq|v ′q ′ ⟩| ⩽√2/√D for q ̸= q ′ and for all |vq⟩ and |v ′q ′ ⟩. Finally, we show that the analogous AMUB relation still holds in the continuous version of this model, which corresponds to a one-dimensional Dirac particle. |
| 47. | Shilan Abo, Jan Soubusta, Kateřina Jiráková, Karol Bartkiewicz, Antonín Černoch, Karel Lemr, Adam Miranowicz Experimental hierarchy of two-qubit quantum correlations without state tomography Scientific Reports, 13 (1), pp. 8564, 2023, ISSN: 2045-2322. @article{abo_experimental_2023, title = {Experimental hierarchy of two-qubit quantum correlations without state tomography}, author = {Shilan Abo and Jan Soubusta and Kateřina Jiráková and Karol Bartkiewicz and Antonín Černoch and Karel Lemr and Adam Miranowicz}, url = {https://www.nature.com/articles/s41598-023-35015-9}, doi = {10.1038/s41598-023-35015-9}, issn = {2045-2322}, year = {2023}, date = {2023-05-26}, urldate = {2023-10-18}, journal = {Scientific Reports}, volume = {13}, number = {1}, pages = {8564}, abstract = {A Werner state, which is the singlet Bell state affected by white noise, is a prototype example of states, which can reveal a hierarchy of quantum entanglement, steering, and Bell nonlocality by controlling the amount of noise. However, experimental demonstrations of this hierarchy in a sufficient and necessary way (i.e., by applying measures or universal witnesses of these quantum correlations) have been mainly based on full quantum state tomography, corresponding to measuring at least 15 real parameters of two-qubit states. Here we report an experimental demonstration of this hierarchy by measuring only six elements of a correlation matrix depending on linear combinations of two-qubit Stokes parameters. We show that our experimental setup can also reveal the hierarchy of these quantum correlations of generalized Werner states, which are any two-qubit pure states affected by white noise.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A Werner state, which is the singlet Bell state affected by white noise, is a prototype example of states, which can reveal a hierarchy of quantum entanglement, steering, and Bell nonlocality by controlling the amount of noise. However, experimental demonstrations of this hierarchy in a sufficient and necessary way (i.e., by applying measures or universal witnesses of these quantum correlations) have been mainly based on full quantum state tomography, corresponding to measuring at least 15 real parameters of two-qubit states. Here we report an experimental demonstration of this hierarchy by measuring only six elements of a correlation matrix depending on linear combinations of two-qubit Stokes parameters. We show that our experimental setup can also reveal the hierarchy of these quantum correlations of generalized Werner states, which are any two-qubit pure states affected by white noise. |
| 46. | Ievgen I. Arkhipov, Adam Miranowicz, Fabrizio Minganti, Şahin K. Özdemir, Franco Nori Nature Communications, 14 (2076), 2023. @article{Arkhipov2023, title = {Dynamically crossing diabolic points while encircling exceptional curves: A programmable symmetric-asymmetric multimode switch}, author = {Ievgen I. Arkhipov and Adam Miranowicz and Fabrizio Minganti and Şahin K. Özdemir and Franco Nori}, url = {https://www.nature.com/articles/s41467-023-37275-5}, doi = {doi.org/10.1038/s41467-023-37275-5}, year = {2023}, date = {2023-04-12}, journal = {Nature Communications}, volume = {14}, number = {2076}, abstract = {Nontrivial spectral properties of non-Hermitian systems can lead to intriguing effects with no counterparts in Hermitian systems. For instance, in a two-mode photonic system, by dynamically winding around an exceptional point (EP) a controlled asymmetric-symmetric mode switching can be realized. That is, the system can either end up in one of its eigenstates, regardless of the initial eigenmode, or it can switch between the two states on demand, by simply controlling the winding direction. However, for multimode systems with higher-order EPs or multiple low-order EPs, the situation can be more involved, and the ability to control asymmetric-symmetric mode switching can be impeded, due to the breakdown of adiabaticity. Here we demonstrate that this difficulty can be overcome by winding around exceptional curves by additionally crossing diabolic points. We consider a four-mode PT-symmetric bosonic system as a platform for experimental realization of such a multimode switch. Our work provides alternative routes for light manipulations in non-Hermitian photonic setups.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nontrivial spectral properties of non-Hermitian systems can lead to intriguing effects with no counterparts in Hermitian systems. For instance, in a two-mode photonic system, by dynamically winding around an exceptional point (EP) a controlled asymmetric-symmetric mode switching can be realized. That is, the system can either end up in one of its eigenstates, regardless of the initial eigenmode, or it can switch between the two states on demand, by simply controlling the winding direction. However, for multimode systems with higher-order EPs or multiple low-order EPs, the situation can be more involved, and the ability to control asymmetric-symmetric mode switching can be impeded, due to the breakdown of adiabaticity. Here we demonstrate that this difficulty can be overcome by winding around exceptional curves by additionally crossing diabolic points. We consider a four-mode PT-symmetric bosonic system as a platform for experimental realization of such a multimode switch. Our work provides alternative routes for light manipulations in non-Hermitian photonic setups. |
| 45. | Grzegorz Chimczak, Anna Kowalewska-Kudłaszyk, Ewelina Lange, Karol Bartkiewicz, Jan Peřina Jr. The effect of thermal photons on exceptional points in coupled resonators. Scientific Reports, 13 , pp. 5859, 2023. @article{Chimczak2023, title = {The effect of thermal photons on exceptional points in coupled resonators.}, author = {Grzegorz Chimczak and Anna Kowalewska-Kudłaszyk and Ewelina Lange and Karol Bartkiewicz and Jan Peřina Jr.}, url = {https://www.nature.com/articles/s41598-023-32864-2}, doi = {https://doi.org/10.1038/s41598-023-32864-2}, year = {2023}, date = {2023-04-11}, journal = {Scientific Reports}, volume = {13}, pages = {5859}, abstract = {We analyse two quantum systems with hidden parity-time ( PT ) symmetry: one is an optical device, whereas another is a superconducting microwave-frequency device. To investigate their symmetry, we introduce a damping frame (DF), in which loss and gain terms for a given Hamiltonian are balanced. We show that the non-Hermitian Hamiltonians of both systems can be tuned to reach an exceptional point (EP), i.e., the point in parameter space at which a transition from broken to unbroken hidden PT symmetry takes place. We calculate a degeneracy of a Liouvillian superoperator, which is called the Liouvillian exceptional point (LEP), and show that, in the optical domain, LEP is equivalent to EP obtained from the non-Hermitian Hamiltonian (HEP). We also report breaking the equivalence between LEP and HEP by a non-zero number of thermal photons for the microwave-frequency system.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We analyse two quantum systems with hidden parity-time ( PT ) symmetry: one is an optical device, whereas another is a superconducting microwave-frequency device. To investigate their symmetry, we introduce a damping frame (DF), in which loss and gain terms for a given Hamiltonian are balanced. We show that the non-Hermitian Hamiltonians of both systems can be tuned to reach an exceptional point (EP), i.e., the point in parameter space at which a transition from broken to unbroken hidden PT symmetry takes place. We calculate a degeneracy of a Liouvillian superoperator, which is called the Liouvillian exceptional point (LEP), and show that, in the optical domain, LEP is equivalent to EP obtained from the non-Hermitian Hamiltonian (HEP). We also report breaking the equivalence between LEP and HEP by a non-zero number of thermal photons for the microwave-frequency system. |
| 44. | Jolanta Natalia Latosińska, Magdalena Latosińska, Janez Seliger, Veselko Žagar, Tomaž Apih, Paweł Grieb Molecules, 28 (8), 2023, ISSN: 1420-3049. @article{molecules28083308, title = {Elucidating the Role of Noncovalent Interactions in Favipiravir, a Drug Active against Various Human RNA Viruses; a 1H-14N NQDR/Periodic DFT/QTAIM/RDS/3D Hirshfeld Surfaces Combined Study}, author = {Jolanta Natalia Latosińska and Magdalena Latosińska and Janez Seliger and Veselko Žagar and Tomaž Apih and Paweł Grieb}, url = {https://www.mdpi.com/1420-3049/28/8/3308}, doi = {10.3390/molecules28083308}, issn = {1420-3049}, year = {2023}, date = {2023-04-07}, journal = {Molecules}, volume = {28}, number = {8}, abstract = {Favipiravir (6-fluoro-3-hydroxypyrazine-2-carboxamide, FPV), an active pharmaceutical component of the drug discovered and registered in March 2014 in Japan under the name Avigan, with an indication for pandemic influenza, has been studied. The study of this compound was prompted by the idea that effective processes of recognition and binding of FPV to the nucleic acid are affected predominantly by the propensity to form intra- and intermolecular interactions. Three nuclear quadrupole resonance experimental techniques, namely 1H-14N cross-relaxation, multiple frequency sweeps, and two-frequency irradiation, followed by solid-state computational modelling (density functional theory supplemented by the quantum theory of atoms in molecules, 3D Hirshfeld Surfaces, and reduced density gradient) approaches were applied. The complete NQR spectrum consisting of nine lines indicating the presence of three chemically inequivalent nitrogen sites in the FPV molecule was detected, and the assignment of lines to particular sites was performed. The description of the nearest vicinity of all three nitrogen atoms was used to characterize the nature of the intermolecular interactions from the perspective of the local single atoms and to draw some conclusions on the nature of the interactions required for effective recognition and binding. The propensity to form the electrostatic N−H···O, N−H···N, and C−H···O intermolecular hydrogen bonds competitive with two intramolecular hydrogen bonds, strong O−H···O and very weak N−H···N, closing the 5-member ring and stiffening the structure, as well as π···π and F···F dispersive interactions, were analysed in detail. The hypothesis regarding the similarity of the interaction pattern in the solid and the RNA template was verified. It was discovered that the -NH2 group in the crystal participates in intermolecular hydrogen bonds N–H···N and N–H···O, in the precatalytic state only in N–H···O, while in the active state in N–H···N and N–H···O hydrogen bonds, which is of importance to link FVP to the RNA template. Our study elucidates the binding modes of FVP (in crystal, precatalytic, and active forms) in detail and should guide the design of more potent analogues targeting SARS-CoV-2. Strong direct binding of FVP-RTP to both the active site and cofactor discovered by us suggests a possible alternative, allosteric mechanism of FVP action, which may explain the scattering of the results of clinical trials or the synergistic effect observed in combined treatment against SARS-CoV-2.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Favipiravir (6-fluoro-3-hydroxypyrazine-2-carboxamide, FPV), an active pharmaceutical component of the drug discovered and registered in March 2014 in Japan under the name Avigan, with an indication for pandemic influenza, has been studied. The study of this compound was prompted by the idea that effective processes of recognition and binding of FPV to the nucleic acid are affected predominantly by the propensity to form intra- and intermolecular interactions. Three nuclear quadrupole resonance experimental techniques, namely 1H-14N cross-relaxation, multiple frequency sweeps, and two-frequency irradiation, followed by solid-state computational modelling (density functional theory supplemented by the quantum theory of atoms in molecules, 3D Hirshfeld Surfaces, and reduced density gradient) approaches were applied. The complete NQR spectrum consisting of nine lines indicating the presence of three chemically inequivalent nitrogen sites in the FPV molecule was detected, and the assignment of lines to particular sites was performed. The description of the nearest vicinity of all three nitrogen atoms was used to characterize the nature of the intermolecular interactions from the perspective of the local single atoms and to draw some conclusions on the nature of the interactions required for effective recognition and binding. The propensity to form the electrostatic N−H···O, N−H···N, and C−H···O intermolecular hydrogen bonds competitive with two intramolecular hydrogen bonds, strong O−H···O and very weak N−H···N, closing the 5-member ring and stiffening the structure, as well as π···π and F···F dispersive interactions, were analysed in detail. The hypothesis regarding the similarity of the interaction pattern in the solid and the RNA template was verified. It was discovered that the -NH2 group in the crystal participates in intermolecular hydrogen bonds N–H···N and N–H···O, in the precatalytic state only in N–H···O, while in the active state in N–H···N and N–H···O hydrogen bonds, which is of importance to link FVP to the RNA template. Our study elucidates the binding modes of FVP (in crystal, precatalytic, and active forms) in detail and should guide the design of more potent analogues targeting SARS-CoV-2. Strong direct binding of FVP-RTP to both the active site and cofactor discovered by us suggests a possible alternative, allosteric mechanism of FVP action, which may explain the scattering of the results of clinical trials or the synergistic effect observed in combined treatment against SARS-CoV-2. |
| 43. | Alberto Mercurio, Shilan Abo, Fabio Mauceri, Enrico Russo, Vincenzo Macrì, Adam Miranowicz, Salvatore Savasta, Omar Di Stefano Pure Dephasing of Light-Matter Systems in the Ultrastrong and Deep-Strong Coupling Regimes Phys. Rev. Lett., 130 , pp. 123601, 2023. @article{Mercurio2023, title = {Pure Dephasing of Light-Matter Systems in the Ultrastrong and Deep-Strong Coupling Regimes}, author = {Alberto Mercurio and Shilan Abo and Fabio Mauceri and Enrico Russo and Vincenzo Macrì and Adam Miranowicz and Salvatore Savasta and Omar Di Stefano}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.130.123601}, doi = {10.1103/PhysRevLett.130.123601}, year = {2023}, date = {2023-03-21}, journal = {Phys. Rev. Lett.}, volume = {130}, pages = {123601}, abstract = {Pure dephasing originates from the nondissipative information exchange between quantum systems and environments, and plays a key role in both spectroscopy and quantum information technology. Often pure dephasing constitutes the main mechanism of decay of quantum correlations. Here we investigate how pure dephasing of one of the components of a hybrid quantum system affects the dephasing rate of the system transitions. We find that, in turn, the interaction, in the case of a light-matter system, can significantly affect the form of the stochastic perturbation describing the dephasing of a subsystem, depending on the adopted gauge. Neglecting this issue can lead to wrong and unphysical results when the interaction becomes comparable to the bare resonance frequencies of subsystems, which correspond to the ultrastrong and deep-strong coupling regimes. We present results for two prototypical models of cavity quantun electrodynamics: the quantum Rabi and the Hopfield model.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Pure dephasing originates from the nondissipative information exchange between quantum systems and environments, and plays a key role in both spectroscopy and quantum information technology. Often pure dephasing constitutes the main mechanism of decay of quantum correlations. Here we investigate how pure dephasing of one of the components of a hybrid quantum system affects the dephasing rate of the system transitions. We find that, in turn, the interaction, in the case of a light-matter system, can significantly affect the form of the stochastic perturbation describing the dephasing of a subsystem, depending on the adopted gauge. Neglecting this issue can lead to wrong and unphysical results when the interaction becomes comparable to the bare resonance frequencies of subsystems, which correspond to the ultrastrong and deep-strong coupling regimes. We present results for two prototypical models of cavity quantun electrodynamics: the quantum Rabi and the Hopfield model. |
| 42. | Andrzej Grudka, Marcin Karczewski, Paweł Kurzyński, Jan Wójcik, Antoni Wójcik Topological invariants in quantum walks Physical Review A, 107 , pp. 032201, 2023. @article{grudka23, title = {Topological invariants in quantum walks}, author = {Andrzej Grudka and Marcin Karczewski and Paweł Kurzyński and Jan Wójcik and Antoni Wójcik}, doi = {10.1103/PhysRevA.107.032201}, year = {2023}, date = {2023-03-01}, journal = {Physical Review A}, volume = {107}, pages = {032201}, abstract = {Discrete-time quantum walks (DTQWs) provide a convenient platform for a realization of many topological phases in noninteracting systems. They often offer more possibilities than systems with a static Hamiltonian. Nevertheless, researchers are still looking for DTQW symmetries protecting topological phases and for definitions of appropriate topological invariants. Although the majority of DTQW studies on this topic focus on the so-called split-step quantum walk, two distinct topological phases can be observed in more basic models. Here we infer topological properties of the basic DTQWs directly from the mapping of the Brillouin zone to the Bloch Hamiltonian. We show that for translation-symmetric systems they can be characterized by a homotopy relative to special points. We also propose a topological invariant corresponding to this concept. This invariant indicates the number of edge states at the interface between two distinct phases.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Discrete-time quantum walks (DTQWs) provide a convenient platform for a realization of many topological phases in noninteracting systems. They often offer more possibilities than systems with a static Hamiltonian. Nevertheless, researchers are still looking for DTQW symmetries protecting topological phases and for definitions of appropriate topological invariants. Although the majority of DTQW studies on this topic focus on the so-called split-step quantum walk, two distinct topological phases can be observed in more basic models. Here we infer topological properties of the basic DTQWs directly from the mapping of the Brillouin zone to the Bloch Hamiltonian. We show that for translation-symmetric systems they can be characterized by a homotopy relative to special points. We also propose a topological invariant corresponding to this concept. This invariant indicates the number of edge states at the interface between two distinct phases. |
| 41. | Kuan-Yi Lee, Jhen-Dong Lin, Adam Miranowicz, Franco Nori, Huan-Yu Ku, Yueh-Nan Chen Steering-enhanced quantum metrology using superpositions of noisy phase shifts Phys. Rev. Res., 5 , pp. 013103, 2023. @article{23prr-lee, title = {Steering-enhanced quantum metrology using superpositions of noisy phase shifts}, author = {Kuan-Yi Lee and Jhen-Dong Lin and Adam Miranowicz and Franco Nori and Huan-Yu Ku and Yueh-Nan Chen}, url = {https://link.aps.org/doi/10.1103/PhysRevResearch.5.013103}, doi = {10.1103/PhysRevResearch.5.013103}, year = {2023}, date = {2023-02-13}, journal = {Phys. Rev. Res.}, volume = {5}, pages = {013103}, publisher = {American Physical Society}, abstract = {Quantum steering is an important correlation in quantum information theory. A recent work [Nat. Commun. 12, 2410 (2021)] showed that quantum steering is also useful for quantum metrology. Here, we extend the exploration of steering-enhanced quantum metrology from single noiseless phase shifts to superpositions of noisy phase shifts. As concrete examples, we consider a control system that manipulates a target system to pass through a superposition of either dephased or depolarized phase shifts channels. We show that using such superpositions of noisy phase shifts can suppress the effects of noise and improve metrology. Furthermore, we also implemented proof-of-principle experiments for a superposition of dephased phase shifts on the IBM quantum experience, demonstrating a clear improvement on metrology.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Quantum steering is an important correlation in quantum information theory. A recent work [Nat. Commun. 12, 2410 (2021)] showed that quantum steering is also useful for quantum metrology. Here, we extend the exploration of steering-enhanced quantum metrology from single noiseless phase shifts to superpositions of noisy phase shifts. As concrete examples, we consider a control system that manipulates a target system to pass through a superposition of either dephased or depolarized phase shifts channels. We show that using such superpositions of noisy phase shifts can suppress the effects of noise and improve metrology. Furthermore, we also implemented proof-of-principle experiments for a superposition of dephased phase shifts on the IBM quantum experience, demonstrating a clear improvement on metrology. |
| 40. | Marceli Koralewski, Małgorzata Paprzycka Journal of Molecular Liquids, 375 , pp. 121375, 2023. @article{Koralewski2023, title = {Faraday effect and refractive index of some imidazolium-based room-temperature ionic liquids and magnetic ionic liquids}, author = {Marceli Koralewski and Małgorzata Paprzycka}, doi = {10.1016/j.molliq.2023.121375}, year = {2023}, date = {2023-02-02}, journal = {Journal of Molecular Liquids}, volume = {375}, pages = {121375}, abstract = {Knowledge of the Faraday effect (FE) is very important in fundamental research and applications. Here, we report FE and refractive index studies for two magnetic ionic liquids (MILs), namely 1-ethyl- and 1-butyl-3-methylimidazolium tetrachloroferrate. Similar studies are also conducted for ionic liquids (ILs) that have a diamagnetic counteranion in place of [FeCl4]. The magnitudes of the Verdet constants of MILs are comparable and exhibit a negative sign. Furthermore, they are about one order larger than those of ILs with a diamagnetic counteranion of a positive sign. The Verdet constant shows monotonic variations as a function of wavelength in the range from 450 to 650 nm and is mainly related to charge transfer transitions in [FeCl4], with bands located in the UV region, though the contribution of d-d transitions in Fe+3 is negligible. A model for describing the measured Verdet constant data as a function of wavelength and temperature is given with respective values of effective Faraday A-, B-, and D-terms. The introduction of an empirical rule allows the estimation of Verdet constants of iron and imidazolium derivative based MILs, which are in some cases very high, thus indicating their potential in photonics applications. Imidazole shows a positive and nearly-two orders lower magnitude of the Verdet constant. The mixture of an MIL and acetonitrile allows the tuning of both the Verdet constant and the refractive index. The refractive indices, thermo-optic coefficients, and electronic polarizabilities of MILs are higher than those of ILs with a diamagnetic counteranion.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Knowledge of the Faraday effect (FE) is very important in fundamental research and applications. Here, we report FE and refractive index studies for two magnetic ionic liquids (MILs), namely 1-ethyl- and 1-butyl-3-methylimidazolium tetrachloroferrate. Similar studies are also conducted for ionic liquids (ILs) that have a diamagnetic counteranion in place of [FeCl4]. The magnitudes of the Verdet constants of MILs are comparable and exhibit a negative sign. Furthermore, they are about one order larger than those of ILs with a diamagnetic counteranion of a positive sign. The Verdet constant shows monotonic variations as a function of wavelength in the range from 450 to 650 nm and is mainly related to charge transfer transitions in [FeCl4], with bands located in the UV region, though the contribution of d-d transitions in Fe+3 is negligible. A model for describing the measured Verdet constant data as a function of wavelength and temperature is given with respective values of effective Faraday A-, B-, and D-terms. The introduction of an empirical rule allows the estimation of Verdet constants of iron and imidazolium derivative based MILs, which are in some cases very high, thus indicating their potential in photonics applications. Imidazole shows a positive and nearly-two orders lower magnitude of the Verdet constant. The mixture of an MIL and acetonitrile allows the tuning of both the Verdet constant and the refractive index. The refractive indices, thermo-optic coefficients, and electronic polarizabilities of MILs are higher than those of ILs with a diamagnetic counteranion. |
| 39. | Jolanta Natalia Latosińska, Magdalena Latosińska, Andrzei Orzeszko, Jan Krzysztof Maurin Molecules, 28 (1), pp. 147, 2023. @article{Latosińska2023, title = {Synthesis and Crystal Structure of Adamantylated 4,5,6,7-tetrahalogeno-1H-benzimidazoles Novel Multi-Target Ligands (Potential CK2, M2 and SARS-CoV-2 Inhibitors). X-ray/DFT/QTAIM/Hirshfeld Surfaces/Molecular Docking Study }, author = {Jolanta Natalia Latosińska and Magdalena Latosińska and Andrzei Orzeszko and Jan Krzysztof Maurin }, doi = {10.3390/molecules28010147}, year = {2023}, date = {2023-01-02}, journal = {Molecules}, volume = {28}, number = {1}, pages = {147}, abstract = {A series of new congeners, 1-[2-(1-adamantyl)ethyl]-1H-benzimidazole (AB) and 1-[2-(1-adamantyl)ethyl]-4,5,6,7-tetrahalogeno-1H-benzimidazole (Hal=Cl, Br, I; tClAB, tBrAB, tIAB), have been synthesized and studied. These novel multi-target ligands combine a benzimidazole ring known to show antitumor activity and an adamantyl moiety showing anti-influenza activity. Their crystal structures were determined by X-ray, while intermolecular interactions were studied using topological Bader’s Quantum Theory of Atoms in Molecules, Hirshfeld Surfaces, CLP and PIXEL approaches. The newly synthesized compounds crystallize within two different space groups, P-1 (AB and tIAB) and P21/c (tClAB and tBrAB). A number of intramolecular hydrogen bonds, C−H⋯Hal (Hal=Cl, Br, I), were found in all halogen-containing congeners studied, but the intermolecular C−H⋯N hydrogen bond was detected only in AB and tIAB, while C−Hal⋯π only in tClAB and tBrAB. The interplay between C−H⋯N and C−H⋯Hal hydrogen bonds and a shift from the strong (C−H⋯Cl) to the very weak (C−H⋯I) attractive interactions upon Hal exchange, supplemented with Hal⋯Hal overlapping, determines the differences in the symmetry of crystalline packing and is crucial from the biological point of view. The hypothesis about the potential dual inhibitor role of the newly synthesized congeners was verified using molecular docking and the congeners were found to be pharmaceutically attractive as Human Casein Kinase 2, CK2, inhibitors, Membrane Matrix 2 Protein, M2, blockers and Severe Acute Respiratory Syndrome Coronavirus 2, SARS-CoV-2, inhibitors. The addition of adamantyl moiety seems to broaden and modify the therapeutic indices of the 4,5,6,7-tetrahalogeno-1H-benzimidazoles.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A series of new congeners, 1-[2-(1-adamantyl)ethyl]-1H-benzimidazole (AB) and 1-[2-(1-adamantyl)ethyl]-4,5,6,7-tetrahalogeno-1H-benzimidazole (Hal=Cl, Br, I; tClAB, tBrAB, tIAB), have been synthesized and studied. These novel multi-target ligands combine a benzimidazole ring known to show antitumor activity and an adamantyl moiety showing anti-influenza activity. Their crystal structures were determined by X-ray, while intermolecular interactions were studied using topological Bader’s Quantum Theory of Atoms in Molecules, Hirshfeld Surfaces, CLP and PIXEL approaches. The newly synthesized compounds crystallize within two different space groups, P-1 (AB and tIAB) and P21/c (tClAB and tBrAB). A number of intramolecular hydrogen bonds, C−H⋯Hal (Hal=Cl, Br, I), were found in all halogen-containing congeners studied, but the intermolecular C−H⋯N hydrogen bond was detected only in AB and tIAB, while C−Hal⋯π only in tClAB and tBrAB. The interplay between C−H⋯N and C−H⋯Hal hydrogen bonds and a shift from the strong (C−H⋯Cl) to the very weak (C−H⋯I) attractive interactions upon Hal exchange, supplemented with Hal⋯Hal overlapping, determines the differences in the symmetry of crystalline packing and is crucial from the biological point of view. The hypothesis about the potential dual inhibitor role of the newly synthesized congeners was verified using molecular docking and the congeners were found to be pharmaceutically attractive as Human Casein Kinase 2, CK2, inhibitors, Membrane Matrix 2 Protein, M2, blockers and Severe Acute Respiratory Syndrome Coronavirus 2, SARS-CoV-2, inhibitors. The addition of adamantyl moiety seems to broaden and modify the therapeutic indices of the 4,5,6,7-tetrahalogeno-1H-benzimidazoles. |
| 38. | Jan Wójcik, Grzegorz Chimczak Electrically coupled optomechanical cavities as a tool for quantum nondemolition measurement Physics Letters A, 490 , pp. 129187, 2023, ISSN: 0375-9601. @article{WOJCIK2023129187, title = {Electrically coupled optomechanical cavities as a tool for quantum nondemolition measurement}, author = {Jan Wójcik and Grzegorz Chimczak}, url = {https://www.sciencedirect.com/science/article/pii/S0375960123005674}, doi = {https://doi.org/10.1016/j.physleta.2023.129187}, issn = {0375-9601}, year = {2023}, date = {2023-01-01}, journal = {Physics Letters A}, volume = {490}, pages = {129187}, abstract = {We present a new model of two electrically coupled optomechanical cavities. This model is based on the recently presented proposal [Physical Review A 103 (2021) 043509]. We found that coupling two optomechanical cavities via Coulomb force leads to cross-Kerr interactions between those cavities. We show that such systems may be ideal for a protocol of quantum non-demolition measurement because it is easy to eliminate the self-phase modulation effect. Moreover, nonlinearities in our model are based on easily adjustable parameters, and therefore, given recent experimental studies, we believe that experimental realization of a cross-Kerr interaction via Coulomb force coupling is feasible.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present a new model of two electrically coupled optomechanical cavities. This model is based on the recently presented proposal [Physical Review A 103 (2021) 043509]. We found that coupling two optomechanical cavities via Coulomb force leads to cross-Kerr interactions between those cavities. We show that such systems may be ideal for a protocol of quantum non-demolition measurement because it is easy to eliminate the self-phase modulation effect. Moreover, nonlinearities in our model are based on easily adjustable parameters, and therefore, given recent experimental studies, we believe that experimental realization of a cross-Kerr interaction via Coulomb force coupling is feasible. |
| 37. | Marceli Koralewski, Małgorzata Paprzycka, Alice Goyal, Krzysztof Gibasiewicz Faraday rotation enhancement for colloidal spherical Au and Ag nanoparticles and their mixtures Journal of Magnetism and Magnetic Materials, 588 , pp. 171461, 2023, ISSN: 0304-8853. @article{Koralewski2023b, title = {Faraday rotation enhancement for colloidal spherical Au and Ag nanoparticles and their mixtures}, author = {Marceli Koralewski and Małgorzata Paprzycka and Alice Goyal and Krzysztof Gibasiewicz}, url = {http://dx.doi.org/10.1016/j.jmmm.2023.171461}, doi = {10.1016/j.jmmm.2023.171461}, issn = {0304-8853}, year = {2023}, date = {2023-01-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {588}, pages = {171461}, publisher = {Elsevier BV}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 36. | Marceli Koralewski, Małgorzata Paprzycka, Katarina Siposova, Oskar Sobotka The kinetics of aggregation of the Aβ1-40 peptide monitored by magnetooptical methods Journal of Magnetism and Magnetic Materials, 587 , pp. 171273, 2023, ISSN: 0304-8853. @article{Koralewski2023c, title = {The kinetics of aggregation of the Aβ1-40 peptide monitored by magnetooptical methods}, author = {Marceli Koralewski and Małgorzata Paprzycka and Katarina Siposova and Oskar Sobotka}, url = {http://dx.doi.org/10.1016/j.jmmm.2023.171273}, doi = {10.1016/j.jmmm.2023.171273}, issn = {0304-8853}, year = {2023}, date = {2023-01-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {587}, pages = {171273}, publisher = {Elsevier BV}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2022 |
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| 35. | Ye-Hong Chen, Adam Miranowicz, Xi Chen, Yan Xia, Franco Nori Enhanced-Fidelity Ultrafast Geometric Quantum Computation Using Strong Classical Drives Phys. Rev. Appl., 18 , pp. 064059, 2022. @article{Chen22geom, title = {Enhanced-Fidelity Ultrafast Geometric Quantum Computation Using Strong Classical Drives}, author = {Ye-Hong Chen and Adam Miranowicz and Xi Chen and Yan Xia and Franco Nori}, url = {https://link.aps.org/doi/10.1103/PhysRevApplied.18.064059}, doi = {10.1103/PhysRevApplied.18.064059}, year = {2022}, date = {2022-12-20}, journal = {Phys. Rev. Appl.}, volume = {18}, pages = {064059}, publisher = {American Physical Society}, abstract = {We propose a general approach to implement ultrafast nonadiabatic geometric single- and two-qubit gates by employing counter-rotating effects. This protocol is compatible with most optimal control methods used in previous rotating-wave approximation (RWA) protocols; thus, it is as robust as (or even more robust than) the RWA protocols. Using counter-rotating effects allows us to apply strong drives. Therefore, we can improve the gate speed by 5–10 times compared to the RWA counterpart for implementing high-fidelity (≥99.99%) gates. Such an ultrafast evolution (nanoseconds, even picoseconds) significantly reduces the influence of decoherence (e.g., the qubit dissipation and dephasing). Moreover, because the counter-rotating effects no longer induce a gate infidelity (in both the weak and strong driving regimes), we can achieve a higher fidelity compared to the RWA protocols. Therefore, in the presence of decoherence, one can implement ultrafast geometric quantum gates with ≥99% fidelities.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose a general approach to implement ultrafast nonadiabatic geometric single- and two-qubit gates by employing counter-rotating effects. This protocol is compatible with most optimal control methods used in previous rotating-wave approximation (RWA) protocols; thus, it is as robust as (or even more robust than) the RWA protocols. Using counter-rotating effects allows us to apply strong drives. Therefore, we can improve the gate speed by 5–10 times compared to the RWA counterpart for implementing high-fidelity (≥99.99%) gates. Such an ultrafast evolution (nanoseconds, even picoseconds) significantly reduces the influence of decoherence (e.g., the qubit dissipation and dephasing). Moreover, because the counter-rotating effects no longer induce a gate infidelity (in both the weak and strong driving regimes), we can achieve a higher fidelity compared to the RWA protocols. Therefore, in the presence of decoherence, one can implement ultrafast geometric quantum gates with ≥99% fidelities. |
| 34. | Jan Perina Jr, Adam Miranowicz, Grzegorz Chimczak, Anna Kowalewska-Kudłaszyk Quantum, 6 , pp. 883, 2022, ISSN: 2521-327X. @article{Perina2022quantum, title = {Quantum Liouvillian exceptional and diabolical points for bosonic fields with quadratic Ħamiltonians: Ŧhe Ħeisenberg-Langevin equation approach}, author = {Jan Perina Jr and Adam Miranowicz and Grzegorz Chimczak and Anna Kowalewska-Kudłaszyk}, url = {https://doi.org/10.22331/q-2022-12-22-883}, doi = {10.22331/q-2022-12-22-883}, issn = {2521-327X}, year = {2022}, date = {2022-12-10}, journal = {Quantum}, volume = {6}, pages = {883}, publisher = {Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften}, abstract = {Equivalent approaches to determine eigenfrequencies of the Liouvillians of open quantum systems are discussed using the solution of the Heisenberg-Langevin equations and the corresponding equations for operator moments. A simple damped two-level atom is analyzed to demonstrate the equivalence of both approaches. The suggested method is used to reveal the structure as well as eigenfrequencies of the dynamics matrices of the corresponding equations of motion and their degeneracies for interacting bosonic modes described by general quadratic Hamiltonians. Quantum Liouvillian exceptional and diabolical points and their degeneracies are explicitly discussed for the case of two modes. Quantum hybrid diabolical exceptional points (inherited, genuine, and induced) and hidden exceptional points, which are not recognized directly in amplitude spectra, are observed. The presented approach via the Heisenberg-Langevin equations paves the general way to a detailed analysis of quantum exceptional and diabolical points in infinitely dimensional open quantum systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Equivalent approaches to determine eigenfrequencies of the Liouvillians of open quantum systems are discussed using the solution of the Heisenberg-Langevin equations and the corresponding equations for operator moments. A simple damped two-level atom is analyzed to demonstrate the equivalence of both approaches. The suggested method is used to reveal the structure as well as eigenfrequencies of the dynamics matrices of the corresponding equations of motion and their degeneracies for interacting bosonic modes described by general quadratic Hamiltonians. Quantum Liouvillian exceptional and diabolical points and their degeneracies are explicitly discussed for the case of two modes. Quantum hybrid diabolical exceptional points (inherited, genuine, and induced) and hidden exceptional points, which are not recognized directly in amplitude spectra, are observed. The presented approach via the Heisenberg-Langevin equations paves the general way to a detailed analysis of quantum exceptional and diabolical points in infinitely dimensional open quantum systems. |
| 33. | Tymoteusz Salamon, Bernhard Irsigler, Debraj Rakshit, Maciej Lewenstein, Tobias Grass, Ravindra W. Chhajlany Flat-band-induced superconductivity in synthetic bilayer optical lattices Phys. Rev. B, 106 , pp. 174503, 2022. @article{PhysRevB.106.174503, title = {Flat-band-induced superconductivity in synthetic bilayer optical lattices}, author = {Tymoteusz Salamon and Bernhard Irsigler and Debraj Rakshit and Maciej Lewenstein and Tobias Grass and Ravindra W. Chhajlany}, url = {https://link.aps.org/doi/10.1103/PhysRevB.106.174503}, doi = {10.1103/PhysRevB.106.174503}, year = {2022}, date = {2022-11-04}, journal = {Phys. Rev. B}, volume = {106}, pages = {174503}, publisher = {American Physical Society}, abstract = {Stacking two layers of graphene with a relative twist angle gives rise to Moiré patterns, which can strongly modify electronic behavior and may lead to unconventional superconductivity. A synthetic version of twisted bilayers can be engineered with cold atoms in optical lattices. Here, the bilayer structure is mimicked through coupling between atomic sublevels, and the twist is achieved by a spatial modulation of this coupling. In the present paper, we investigate the superconducting behavior of fermionic atoms in such a synthetic twisted bilayer lattice. Attractive interactions between the atoms are treated on the mean-field level, and the superconducting behavior is analyzed via the self-consistently determined pairing gap. A strong enhancement of the pairing gap is found when a quasi-flat band structure occurs at the Fermi surface, reflecting the prominent role played by the twist on the superconductivity. The tunability of interactions allows for the switching of superconducting correlations from intra (synthetic) layer to inter (synthetic) layer. This includes also the intermediate scenario, in which the competition between inter- and intra-layer coupling completely destroys the superconducting behavior, resulting in re-entrant superconductivity upon tuning of the interactions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Stacking two layers of graphene with a relative twist angle gives rise to Moiré patterns, which can strongly modify electronic behavior and may lead to unconventional superconductivity. A synthetic version of twisted bilayers can be engineered with cold atoms in optical lattices. Here, the bilayer structure is mimicked through coupling between atomic sublevels, and the twist is achieved by a spatial modulation of this coupling. In the present paper, we investigate the superconducting behavior of fermionic atoms in such a synthetic twisted bilayer lattice. Attractive interactions between the atoms are treated on the mean-field level, and the superconducting behavior is analyzed via the self-consistently determined pairing gap. A strong enhancement of the pairing gap is found when a quasi-flat band structure occurs at the Fermi surface, reflecting the prominent role played by the twist on the superconductivity. The tunability of interactions allows for the switching of superconducting correlations from intra (synthetic) layer to inter (synthetic) layer. This includes also the intermediate scenario, in which the competition between inter- and intra-layer coupling completely destroys the superconducting behavior, resulting in re-entrant superconductivity upon tuning of the interactions. |
| 32. | Shilan Abo, Grzegorz Chimczak, Anna Kowalewska-Kudłaszyk, Jan Peřina Jr, Ravindra W. Chhajlany, Adam Miranowicz Scientific Reports, 12 , pp. 17655, 2022, ISSN: 2045-2322. @article{shilan2022, title = {Hybrid photon–phonon blockade}, author = {Shilan Abo and Grzegorz Chimczak and Anna Kowalewska-Kudłaszyk and Jan Peřina Jr and Ravindra W. Chhajlany and Adam Miranowicz }, url = {https://www.nature.com/articles/s41598-022-21267-4}, doi = {https://doi.org/10.1038/s41598-022-21267-4}, issn = {2045-2322}, year = {2022}, date = {2022-10-21}, journal = {Scientific Reports}, volume = {12}, pages = {17655}, abstract = {We describe a novel type of blockade in a hybrid mode generated by linear coupling of photonic and phononic modes. We refer to this effect as hybrid photon–phonon blockade and show how it can be generated and detected in a driven nonlinear optomechanical superconducting system. Thus, we study boson-number correlations in the photon, phonon, and hybrid modes in linearly coupled microwave and mechanical resonators with a superconducting qubit inserted in one of them. We find such system parameters for which we observe eight types of different combinations of either blockade or tunnelling effects (defined via the sub- and super-Poissonian statistics, respectively) for photons, phonons, and hybrid bosons. In particular, we find that the hybrid photon–phonon blockade can be generated by mixing the photonic and phononic modes which do not exhibit blockade.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We describe a novel type of blockade in a hybrid mode generated by linear coupling of photonic and phononic modes. We refer to this effect as hybrid photon–phonon blockade and show how it can be generated and detected in a driven nonlinear optomechanical superconducting system. Thus, we study boson-number correlations in the photon, phonon, and hybrid modes in linearly coupled microwave and mechanical resonators with a superconducting qubit inserted in one of them. We find such system parameters for which we observe eight types of different combinations of either blockade or tunnelling effects (defined via the sub- and super-Poissonian statistics, respectively) for photons, phonons, and hybrid bosons. In particular, we find that the hybrid photon–phonon blockade can be generated by mixing the photonic and phononic modes which do not exhibit blockade. |
| 31. | E.S. Gevorkyan, V.P. Nerubatskyi, R.V. Vovk, V.O. Chyshkala, S.V. Lytovchenko, O.M. Morozova, Jolanta Natalia Latosińska Acta Physica Polonica A, 142 (4), pp. 529, 2022. @article{latosinska2022, title = {Features of synthesis of Y2Ti2O7 ceramics for the purpose of obtaining dispersion-strengthened steels}, author = {E.S. Gevorkyan and V.P. Nerubatskyi and R.V. Vovk and V.O. Chyshkala and S.V. Lytovchenko and O.M. Morozova and Jolanta Natalia Latosińska}, url = {http://przyrbwn.icm.edu.pl/APP/SPIS/a142-4.html}, doi = {10.12693/APhysPolA.142.529}, year = {2022}, date = {2022-10-17}, journal = {Acta Physica Polonica A}, volume = {142}, number = {4}, pages = {529}, abstract = {The method of electron beam heating of a mixture of yttrium and zirconium oxides for the synthesis of complex oxides has been implemented. It is established that the applied technology of melting the mixture of oxides leads to the formation of fluorite phases. It is determined that homogenization of the initial mixture of oxides should be carried out in a high-energy mill, which will reduce the temperature and duration of the synthesis of complex oxide compounds, including the desired structure of pyrochlorine. It is proposed to improve the technique of intensive thermal influence on the process of pyrochlorine synthesis by using an equiatomic alloy Y-Ti (65 wt. Y-35 wt Ti), which has been smelted using the arc melting method in an argon atmosphere. It was found that hydrogen saturation reduces the efficiency of pyrochlorine synthesis and increases the grain size, which may be associated with grain growth at the stage of hydrogen saturation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The method of electron beam heating of a mixture of yttrium and zirconium oxides for the synthesis of complex oxides has been implemented. It is established that the applied technology of melting the mixture of oxides leads to the formation of fluorite phases. It is determined that homogenization of the initial mixture of oxides should be carried out in a high-energy mill, which will reduce the temperature and duration of the synthesis of complex oxide compounds, including the desired structure of pyrochlorine. It is proposed to improve the technique of intensive thermal influence on the process of pyrochlorine synthesis by using an equiatomic alloy Y-Ti (65 wt. Y-35 wt Ti), which has been smelted using the arc melting method in an argon atmosphere. It was found that hydrogen saturation reduces the efficiency of pyrochlorine synthesis and increases the grain size, which may be associated with grain growth at the stage of hydrogen saturation. |
| 30. | Andrzej Grudka, Antoni Wójcik Comment on 'Quantum principle of relativity' New J. Phys., 24 (9), pp. 098001, 2022. @article{Grudka2022, title = {Comment on 'Quantum principle of relativity'}, author = { Andrzej Grudka and Antoni Wójcik }, url = {https://iopscience.iop.org/article/10.1088/1367-2630/ac924e/meta}, doi = {10.1088/1367-2630/ac924e}, year = {2022}, date = {2022-10-03}, journal = {New J. Phys.}, volume = {24}, number = {9}, pages = {098001}, abstract = {Recently Dragan and Ekert (2020 New. J. Phys. 22 033038) presented arguments that probabilistic dynamics inherent in the realm of quantum physics is related to the propagation of superluminal particles. Moreover they argue that existence of such particles is a natural consequence of the principle of relativity. We show that the proposed extension of the Lorentz transformation can be interpreted in a natural way without invoking superluminal phenomena.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Recently Dragan and Ekert (2020 New. J. Phys. 22 033038) presented arguments that probabilistic dynamics inherent in the realm of quantum physics is related to the propagation of superluminal particles. Moreover they argue that existence of such particles is a natural consequence of the principle of relativity. We show that the proposed extension of the Lorentz transformation can be interpreted in a natural way without invoking superluminal phenomena. |
| 29. | Jan Roik, Karol Bartkiewicz, Antonín Černoch, Karel Lemr Entanglement quantification from collective measurements processed by machine learning Physics Letters A, 446 , pp. 128270, 2022, ISSN: 0375-9601. @article{ROIK2022128270b, title = {Entanglement quantification from collective measurements processed by machine learning}, author = {Jan Roik and Karol Bartkiewicz and Antonín Černoch and Karel Lemr}, url = {https://www.sciencedirect.com/science/article/pii/S0375960122003528}, doi = {https://doi.org/10.1016/j.physleta.2022.128270}, issn = {0375-9601}, year = {2022}, date = {2022-09-15}, journal = {Physics Letters A}, volume = {446}, pages = {128270}, abstract = {This paper investigates how to reduce the number of measurement configurations needed for sufficiently precise entanglement quantification. Instead of analytical formulae, we employ artificial neural networks to predict the amount of entanglement in a quantum state based on results of collective measurements (simultaneous measurements on multiple instances of the investigated state). We consider collective measurement limited to two copies of the investigated state. This approach allows us to explore the precision of entanglement quantification as a function of measurement configurations in a relevant scenario for practical quantum communications. For the purpose of our research, we consider general two-qubit states and their negativity as entanglement quantifier. We outline the benefits of this approach in future quantum communication networks.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper investigates how to reduce the number of measurement configurations needed for sufficiently precise entanglement quantification. Instead of analytical formulae, we employ artificial neural networks to predict the amount of entanglement in a quantum state based on results of collective measurements (simultaneous measurements on multiple instances of the investigated state). We consider collective measurement limited to two copies of the investigated state. This approach allows us to explore the precision of entanglement quantification as a function of measurement configurations in a relevant scenario for practical quantum communications. For the purpose of our research, we consider general two-qubit states and their negativity as entanglement quantifier. We outline the benefits of this approach in future quantum communication networks. |
| 28. | Wei Qin, Adam Miranowicz, Franco Nori Beating the 3 dB Limit for Intracavity Squeezing and Its Application to Nondemolition Qubit Readout Phys. Rev. Lett., 129 , pp. 123602, 2022. @article{Qin2022, title = {Beating the 3 dB Limit for Intracavity Squeezing and Its Application to Nondemolition Qubit Readout}, author = {Wei Qin and Adam Miranowicz and Franco Nori}, url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.123602}, doi = {10.1103/PhysRevLett.129.123602}, year = {2022}, date = {2022-09-14}, journal = {Phys. Rev. Lett.}, volume = {129}, pages = {123602}, abstract = {While the squeezing of a propagating field can, in principle, be made arbitrarily strong, the cavity-field squeezing is subject to the well-known 3 dB limit, and thus has limited applications. Here, we propose the use of a fully quantum degenerate parametric amplifier (DPA) to beat this squeezing limit. Specifically, we show that by simply applying a two-tone driving to the signal mode, the pump mode can, counterintuitively, be driven by the photon loss of the signal mode into a squeezed steady state with, in principle, an arbitrarily high degree of squeezing. Furthermore, we demonstrate that this intracavity squeezing can increase the signal-to-noise ratio of longitudinal qubit readout exponentially with the degree of squeezing. Correspondingly, an improvement of the measurement error by many orders of magnitude can be achieved even for modest parameters. In stark contrast, using intracavity squeezing of the semiclassical DPA cannot practically increase the signal-to-noise ratio and thus improve the measurement error. Our results extend the range of applications of DPAs and open up new opportunities for modern quantum technologies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } While the squeezing of a propagating field can, in principle, be made arbitrarily strong, the cavity-field squeezing is subject to the well-known 3 dB limit, and thus has limited applications. Here, we propose the use of a fully quantum degenerate parametric amplifier (DPA) to beat this squeezing limit. Specifically, we show that by simply applying a two-tone driving to the signal mode, the pump mode can, counterintuitively, be driven by the photon loss of the signal mode into a squeezed steady state with, in principle, an arbitrarily high degree of squeezing. Furthermore, we demonstrate that this intracavity squeezing can increase the signal-to-noise ratio of longitudinal qubit readout exponentially with the degree of squeezing. Correspondingly, an improvement of the measurement error by many orders of magnitude can be achieved even for modest parameters. In stark contrast, using intracavity squeezing of the semiclassical DPA cannot practically increase the signal-to-noise ratio and thus improve the measurement error. Our results extend the range of applications of DPAs and open up new opportunities for modern quantum technologies. |
| 27. | C. Lagoin, U. Bhattacharya, T. Grass, Ravindra W. Chhajlany, T. Salamon, K. Baldwin, L. Pfeiffer, M. Lewenstein, M. Holzmann, F. Dubin Extended Bose–Hubbard model with dipolar excitons Nature, 609 , pp. 485–489, 2022. @article{Lagoin2022, title = {Extended Bose–Hubbard model with dipolar excitons}, author = {C. Lagoin and U. Bhattacharya and T. Grass and Ravindra W. Chhajlany and T. Salamon and K. Baldwin and L. Pfeiffer and M. Lewenstein and M. Holzmann and F. Dubin}, url = {https://www.nature.com/articles/s41586-022-05123-z}, doi = {10.1038/s41586-022-05123-z}, year = {2022}, date = {2022-09-14}, journal = {Nature}, volume = {609}, pages = {485–489}, abstract = {The Hubbard model constitutes one of the most celebrated theoretical frameworks of condensed-matter physics. It describes strongly correlated phases of interacting quantum particles confined in lattice potentials. For bosons, the Hubbard Hamiltonian has been deeply scrutinized for short-range on-site interactions. However, accessing longer-range couplings has remained elusive experimentally. This marks the frontier towards the extended Bose–Hubbard Hamiltonian, which enables insulating ordered phases at fractional lattice fillings. Here we implement this Hamiltonian by confining semiconductor dipolar excitons in an artificial two-dimensional square lattice. Strong dipolar repulsions between nearest-neighbour lattice sites then stabilize an insulating state at half filling. This characteristic feature of the extended Bose–Hubbard model exhibits the signatures theoretically expected for a chequerboard spatial order. Our work thus highlights that dipolar excitons enable controlled implementations of boson-like arrays with strong off-site interactions, in lattices with programmable geometries and more than 100 sites.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The Hubbard model constitutes one of the most celebrated theoretical frameworks of condensed-matter physics. It describes strongly correlated phases of interacting quantum particles confined in lattice potentials. For bosons, the Hubbard Hamiltonian has been deeply scrutinized for short-range on-site interactions. However, accessing longer-range couplings has remained elusive experimentally. This marks the frontier towards the extended Bose–Hubbard Hamiltonian, which enables insulating ordered phases at fractional lattice fillings. Here we implement this Hamiltonian by confining semiconductor dipolar excitons in an artificial two-dimensional square lattice. Strong dipolar repulsions between nearest-neighbour lattice sites then stabilize an insulating state at half filling. This characteristic feature of the extended Bose–Hubbard model exhibits the signatures theoretically expected for a chequerboard spatial order. Our work thus highlights that dipolar excitons enable controlled implementations of boson-like arrays with strong off-site interactions, in lattices with programmable geometries and more than 100 sites. |
| 26. | Rui Xu, Deng-Gao Lai, Bang-Pin Hou, Adam Miranowicz, Franco Nori Phys. Rev. A, 106 , pp. 033509, 2022. @article{Xu2022, title = {Millionfold improvement in multivibration-feedback optomechanical refrigeration via auxiliary mechanical coupling}, author = {Rui Xu and Deng-Gao Lai and Bang-Pin Hou and Adam Miranowicz and Franco Nori}, url = {https://journals.aps.org/pra/abstract/10.1103/PhysRevA.106.033509}, doi = {10.1103/PhysRevA.106.033509}, year = {2022}, date = {2022-09-13}, journal = {Phys. Rev. A}, volume = {106}, pages = {033509}, abstract = {The simultaneous ground-state refrigeration of multiple vibrational modes is a prerequisite for observing significant quantum effects of multiple-vibration systems. Here we propose how to realize a large amplification in the net-refrigeration rates based on cavity optomechanics and to largely improve the cooling performance of multivibration modes beyond the resolved-sideband regime. By employing an auxiliary mechanical coupling (AMC) between two mechanical vibrations, the dark mode, which is induced by the coupling of these vibrational modes to a common optical mode and cuts off cooling channels, can be fully removed. We use fully analytical treatments for the effective mechanical susceptibilities and net-cooling rates and find that when the AMC is turned on, the amplification of the net-refrigeration rates by more than six orders of magnitude can be observed. In particular, we reveal that the simultaneous ground-state cooling beyond the resolved-sideband regime arises from the introduced AMC, without which it vanishes. Our work paves the way for quantum control of multiple vibrational modes in the bad-cavity regime.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The simultaneous ground-state refrigeration of multiple vibrational modes is a prerequisite for observing significant quantum effects of multiple-vibration systems. Here we propose how to realize a large amplification in the net-refrigeration rates based on cavity optomechanics and to largely improve the cooling performance of multivibration modes beyond the resolved-sideband regime. By employing an auxiliary mechanical coupling (AMC) between two mechanical vibrations, the dark mode, which is induced by the coupling of these vibrational modes to a common optical mode and cuts off cooling channels, can be fully removed. We use fully analytical treatments for the effective mechanical susceptibilities and net-cooling rates and find that when the AMC is turned on, the amplification of the net-refrigeration rates by more than six orders of magnitude can be observed. In particular, we reveal that the simultaneous ground-state cooling beyond the resolved-sideband regime arises from the introduced AMC, without which it vanishes. Our work paves the way for quantum control of multiple vibrational modes in the bad-cavity regime. |
| 25. | Ye-Hong Chen, Roberto Stassi, Wei Qin, Adam Miranowicz, Franco Nori Fault-Tolerant Multiqubit Geometric Entangling Gates Using Photonic Cat-State Qubits Phys. Rev. Applied, 18 , pp. 024076, 2022. @article{Chen2022, title = {Fault-Tolerant Multiqubit Geometric Entangling Gates Using Photonic Cat-State Qubits}, author = {Ye-Hong Chen and Roberto Stassi and Wei Qin and Adam Miranowicz and Franco Nori}, url = {https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.18.024076}, doi = {10.1103/PhysRevApplied.18.024076}, year = {2022}, date = {2022-08-29}, journal = {Phys. Rev. Applied}, volume = {18}, pages = {024076}, abstract = {We propose a theoretical protocol to implement multiqubit geometric gates (i.e., the Mølmer-Sørensen gate) using photonic cat-state qubits. These cat-state qubits stored in high-Q resonators are promising for hardware-efficient universal quantum computing. Specifically, in the limit of strong two-photon drivings, phase-flip errors of the cat-state qubits are effectively suppressed, leaving only a bit-flip error to be corrected. Because this dominant error commutes with the evolution operator, our protocol preserves the error bias, and, thus, can lower the code-capacity threshold for error correction. A geometric evolution guarantees the robustness of the protocol against stochastic noise along the evolution path. Moreover, by changing detunings of the cavity-cavity couplings at a proper time, the protocol can be robust against parameter imperfections (e.g., the total evolution time) without introducing extra noises into the system. As a result, the gate can produce multimode entangled cat states in a short time with high fidelities.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose a theoretical protocol to implement multiqubit geometric gates (i.e., the Mølmer-Sørensen gate) using photonic cat-state qubits. These cat-state qubits stored in high-Q resonators are promising for hardware-efficient universal quantum computing. Specifically, in the limit of strong two-photon drivings, phase-flip errors of the cat-state qubits are effectively suppressed, leaving only a bit-flip error to be corrected. Because this dominant error commutes with the evolution operator, our protocol preserves the error bias, and, thus, can lower the code-capacity threshold for error correction. A geometric evolution guarantees the robustness of the protocol against stochastic noise along the evolution path. Moreover, by changing detunings of the cavity-cavity couplings at a proper time, the protocol can be robust against parameter imperfections (e.g., the total evolution time) without introducing extra noises into the system. As a result, the gate can produce multimode entangled cat states in a short time with high fidelities. |
| 24. | Deng-Gao Lai, Ye-Hong Chen, Wei Qin, Adam Miranowicz, Franco Nori Tripartite optomechanical entanglement via optical-dark-mode control Phys. Rev. Research, 4 , pp. 033112, 2022. @article{Lai2022, title = {Tripartite optomechanical entanglement via optical-dark-mode control}, author = {Deng-Gao Lai and Ye-Hong Chen and Wei Qin and Adam Miranowicz and Franco Nori}, url = {https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.4.033112}, doi = {10.1103/PhysRevResearch.4.033112}, year = {2022}, date = {2022-08-10}, journal = {Phys. Rev. Research}, volume = {4}, pages = {033112}, abstract = {We propose how to generate a tripartite light-vibration entanglement by controlling an optical dark mode (ODM), which is induced by the coupling of two optical modes to a common vibrational mode. This ODM is decoupled from the vibration, and it can be controlled on demand by employing a synthetic gauge field, which can enable efficient switching between the ODM-unbreaking and ODM-breaking regimes. We find that the tripartite optomechanical entanglement is largely suppressed in the ODM-unbreaking regime, but it is significantly enhanced in the ODM-breaking regime. In particular, the noise robustness of quantum entanglement in the ODM-breaking regime can be more than twice than that in the ODM-unbreaking regime. This study offers a method for protecting and enhancing fragile quantum resources and for constructing noise-tolerant and dark-mode-immune quantum processors and entangled networks.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose how to generate a tripartite light-vibration entanglement by controlling an optical dark mode (ODM), which is induced by the coupling of two optical modes to a common vibrational mode. This ODM is decoupled from the vibration, and it can be controlled on demand by employing a synthetic gauge field, which can enable efficient switching between the ODM-unbreaking and ODM-breaking regimes. We find that the tripartite optomechanical entanglement is largely suppressed in the ODM-unbreaking regime, but it is significantly enhanced in the ODM-breaking regime. In particular, the noise robustness of quantum entanglement in the ODM-breaking regime can be more than twice than that in the ODM-unbreaking regime. This study offers a method for protecting and enhancing fragile quantum resources and for constructing noise-tolerant and dark-mode-immune quantum processors and entangled networks. |
| 23. | Deng-Gao Lai, Wei Qin, Adam Miranowicz, Franco Nori Phys. Rev. Research, 4 , pp. 033102, 2022. @article{Lai2022b, title = {Efficient optomechanical refrigeration of two vibrations via an auxiliary feedback loop: Giant enhancement in mechanical susceptibilities and net cooling rates}, author = {Deng-Gao Lai and Wei Qin and Adam Miranowicz and Franco Nori}, url = {https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.4.033102}, doi = {10.1103/PhysRevResearch.4.033102}, year = {2022}, date = {2022-08-05}, journal = {Phys. Rev. Research}, volume = {4}, pages = {033102}, abstract = {We propose a method to realize the simultaneous ground-state refrigeration of two vibrational modes beyond the resolved-sideband regime via an auxiliary feedback loop (AFL). This is realized by introducing the AFL to break the dark mode, which is formed by two vibrational modes coupled to a common cavity-field mode. We obtain analytical results of the effective mechanical susceptibilities and net-refrigeration rates, and find that in the presence of the AFL a giant enhancement can be achieved for these susceptibilities and refrigeration rates. Remarkably, the net-cooling rates under the AFL mechanism can be up to four orders of magnitude larger than those in cases without the AFL. Moreover, we show that the simultaneous ground-state refrigeration arises from the AFL mechanism, without which it vanishes. This is because in the absence of the AFL, the dark mode prevents energy extraction through the cooling channels. However, by introducing the AFL, dark-mode breaking rebuilds the refrigeration channels, and, as a result, leads to the simultaneous cooling of these vibrations. Our approach has remarkable flexibility and scalability and can be extended to the simultaneous refrigeration of a large number of vibrations beyond the resolved-sideband regime.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose a method to realize the simultaneous ground-state refrigeration of two vibrational modes beyond the resolved-sideband regime via an auxiliary feedback loop (AFL). This is realized by introducing the AFL to break the dark mode, which is formed by two vibrational modes coupled to a common cavity-field mode. We obtain analytical results of the effective mechanical susceptibilities and net-refrigeration rates, and find that in the presence of the AFL a giant enhancement can be achieved for these susceptibilities and refrigeration rates. Remarkably, the net-cooling rates under the AFL mechanism can be up to four orders of magnitude larger than those in cases without the AFL. Moreover, we show that the simultaneous ground-state refrigeration arises from the AFL mechanism, without which it vanishes. This is because in the absence of the AFL, the dark mode prevents energy extraction through the cooling channels. However, by introducing the AFL, dark-mode breaking rebuilds the refrigeration channels, and, as a result, leads to the simultaneous cooling of these vibrations. Our approach has remarkable flexibility and scalability and can be extended to the simultaneous refrigeration of a large number of vibrations beyond the resolved-sideband regime. |
| 22. | Deng-Gao Lai, Jie-Qiao Liao, Adam Miranowicz, Franco Nori Noise-Tolerant Optomechanical Entanglement via Synthetic Magnetism Phys. Rev. Lett., 129 , pp. 063602, 2022. @article{Lai2022c, title = {Noise-Tolerant Optomechanical Entanglement via Synthetic Magnetism}, author = {Deng-Gao Lai and Jie-Qiao Liao and Adam Miranowicz and Franco Nori}, url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.063602}, doi = {10.1103/PhysRevLett.129.063602}, year = {2022}, date = {2022-08-03}, journal = {Phys. Rev. Lett.}, volume = {129}, pages = {063602}, abstract = {Entanglement of light and multiple vibrations is a key resource for multichannel quantum information processing and memory. However, entanglement generation is generally suppressed, or even fully destroyed, by the dark-mode (DM) effect induced by the coupling of multiple degenerate or near-degenerate vibrational modes to a common optical mode. Here we propose how to generate optomechanical entanglement via DM breaking induced by synthetic magnetism. We find that at nonzero temperature, light and vibrations are separable in the DM-unbreaking regime but entangled in the DM-breaking regime. Remarkably, the threshold thermal phonon number for preserving entanglement in our simulations has been observed to be up to 3 orders of magnitude stronger than that in the DM-unbreaking regime. The application of the DM-breaking mechanism to optomechanical networks can make noise-tolerant entanglement networks feasible. These results are quite general and can initiate advances in quantum resources with immunity against both dark modes and thermal noise.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Entanglement of light and multiple vibrations is a key resource for multichannel quantum information processing and memory. However, entanglement generation is generally suppressed, or even fully destroyed, by the dark-mode (DM) effect induced by the coupling of multiple degenerate or near-degenerate vibrational modes to a common optical mode. Here we propose how to generate optomechanical entanglement via DM breaking induced by synthetic magnetism. We find that at nonzero temperature, light and vibrations are separable in the DM-unbreaking regime but entangled in the DM-breaking regime. Remarkably, the threshold thermal phonon number for preserving entanglement in our simulations has been observed to be up to 3 orders of magnitude stronger than that in the DM-unbreaking regime. The application of the DM-breaking mechanism to optomechanical networks can make noise-tolerant entanglement networks feasible. These results are quite general and can initiate advances in quantum resources with immunity against both dark modes and thermal noise. |
| 21. | Huan-Yu Ku, Josef Kadlec, Antonín Černoch, Marco Túlio Quintino, Wenbin Zhou, Karel Lemr, Neill Lambert, Adam Miranowicz, Shin-Liang Chen, Franco Nori, Yueh-Nan Chen Quantifying Quantumness of Channels Without Entanglement PRX Quantum, 3 , pp. 020338, 2022. @article{Ku2022, title = {Quantifying Quantumness of Channels Without Entanglement}, author = {Huan-Yu Ku and Josef Kadlec and Antonín Černoch and Marco Túlio Quintino and Wenbin Zhou and Karel Lemr and Neill Lambert and Adam Miranowicz and Shin-Liang Chen and Franco Nori and Yueh-Nan Chen}, url = {https://journals.aps.org/prxquantum/abstract/10.1103/PRXQuantum.3.020338}, doi = {10.1103/PRXQuantum.3.020338}, year = {2022}, date = {2022-05-19}, journal = {PRX Quantum}, volume = {3}, pages = {020338}, abstract = {Quantum channels breaking entanglement, incompatibility, or nonlocality are defined as such because they are not useful for entanglement-based, one-sided device-independent, or device-independent quantum-information processing, respectively. Here, we show that such breaking channels are related to complementary tests of macrorealism, i.e., temporal separability, channel unsteerability, temporal unsteerability, and the temporal Bell inequality. To demonstrate this we first define a steerability-breaking channel, which is conceptually similar to entanglement and nonlocality-breaking channels and prove that it is identical to an incompatibility-breaking channel. A hierarchy of quantum nonbreaking channels is derived, akin to the existing hierarchy relations for temporal and spatial quantum correlations. We then introduce the concept of channels that break temporal correlations, explain how they are related to the standard breaking channels, and prove the following results. (1) A robustness-based measure for non-entanglement-breaking channels can be probed by temporal nonseparability. (2) A non-steerability-breaking channel can be quantified by channel steering. (3) Temporal steerability and nonmacrorealism can be used for, respectively, distinguishing unital steerability-breaking channels and nonlocality-breaking channels for a maximally entangled state. Finally, a two-dimensional depolarizing channel is experimentally implemented as a proof-of-principle example to demonstrate the hierarchy relation of nonbreaking channels using temporal quantum correlations.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Quantum channels breaking entanglement, incompatibility, or nonlocality are defined as such because they are not useful for entanglement-based, one-sided device-independent, or device-independent quantum-information processing, respectively. Here, we show that such breaking channels are related to complementary tests of macrorealism, i.e., temporal separability, channel unsteerability, temporal unsteerability, and the temporal Bell inequality. To demonstrate this we first define a steerability-breaking channel, which is conceptually similar to entanglement and nonlocality-breaking channels and prove that it is identical to an incompatibility-breaking channel. A hierarchy of quantum nonbreaking channels is derived, akin to the existing hierarchy relations for temporal and spatial quantum correlations. We then introduce the concept of channels that break temporal correlations, explain how they are related to the standard breaking channels, and prove the following results. (1) A robustness-based measure for non-entanglement-breaking channels can be probed by temporal nonseparability. (2) A non-steerability-breaking channel can be quantified by channel steering. (3) Temporal steerability and nonmacrorealism can be used for, respectively, distinguishing unital steerability-breaking channels and nonlocality-breaking channels for a maximally entangled state. Finally, a two-dimensional depolarizing channel is experimentally implemented as a proof-of-principle example to demonstrate the hierarchy relation of nonbreaking channels using temporal quantum correlations. |
| 20. | Chia-Yi Ju, Adam Miranowicz, Fabrizio Minganti, Chuan-Tsung Chan, Guang-Yin Chen, Franco Nori Phys. Rev. Research, 4 , pp. 023070, 2022. @article{Ju22prr, title = {Einstein's quantum elevator: Hermitization of non-Hermitian Hamiltonians via a generalized vielbein formalism}, author = {Chia-Yi Ju and Adam Miranowicz and Fabrizio Minganti and Chuan-Tsung Chan and Guang-Yin Chen and Franco Nori}, url = {https://link.aps.org/doi/10.1103/PhysRevResearch.4.023070}, doi = {10.1103/PhysRevResearch.4.023070}, year = {2022}, date = {2022-04-01}, journal = {Phys. Rev. Research}, volume = {4}, pages = {023070}, publisher = {American Physical Society}, abstract = {The formalism for non-Hermitian quantum systems sometimes blurs the underlying physics. We present a systematic study of the vielbeinlike formalism which transforms the Hilbert space bundles of non-Hermitian systems into the conventional ones, rendering the induced Hamiltonian to be Hermitian. In other words, any non-Hermitian Hamiltonian can be “transformed” into a Hermitian one without altering the physics. Thus we show how to find a reference frame (corresponding to Einstein's quantum elevator) in which a non-Hermitian system, equipped with a nontrivial Hilbert space metric, reduces to a Hermitian system within the standard formalism of quantum mechanics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The formalism for non-Hermitian quantum systems sometimes blurs the underlying physics. We present a systematic study of the vielbeinlike formalism which transforms the Hilbert space bundles of non-Hermitian systems into the conventional ones, rendering the induced Hamiltonian to be Hermitian. In other words, any non-Hermitian Hamiltonian can be “transformed” into a Hermitian one without altering the physics. Thus we show how to find a reference frame (corresponding to Einstein's quantum elevator) in which a non-Hermitian system, equipped with a nontrivial Hilbert space metric, reduces to a Hermitian system within the standard formalism of quantum mechanics. |
| 19. | Yi-Hao Kang, Ye-Hong Chen, Xin Wang, Jie Song, Yan Xia, Adam Miranowicz, Shi-Biao Zheng, Franco Nori Phys. Rev. Research, 4 , pp. 013233, 2022. @article{Kang2022, title = {Nonadiabatic geometric quantum computation with cat-state qubits via invariant-based reverse engineering}, author = {Yi-Hao Kang and Ye-Hong Chen and Xin Wang and Jie Song and Yan Xia and Adam Miranowicz and Shi-Biao Zheng and Franco Nori}, url = {https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.4.013233}, doi = {10.1103/PhysRevResearch.4.013233}, year = {2022}, date = {2022-03-28}, journal = {Phys. Rev. Research}, volume = {4}, pages = {013233}, abstract = {We propose a protocol to realize nonadiabatic geometric quantum computation of small-amplitude Schrödinger cat qubits via invariant-based reverse engineering. We consider a system with a two-photon driven Kerr nonlinearity, which can generate a pair of dressed even and odd coherent states (i.e., Schrödinger cat states) for fault-tolerant quantum computations. An additional coherent field is applied to linearly drive a cavity mode, to induce oscillations between dressed cat states. By designing this linear drive with invariant-based reverse engineering, we show how to implement nonadiabatic geometric quantum computation with cat qubits. The performance of the protocol is estimated by taking into account the influence of systematic errors, additive white Gaussian noise, 1/f noise, and decoherence including photon loss and dephasing. Numerical results demonstrate that our protocol is robust against these negative factors. Therefore, this protocol may provide a feasible method for nonadiabatic geometric quantum computation in bosonic systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose a protocol to realize nonadiabatic geometric quantum computation of small-amplitude Schrödinger cat qubits via invariant-based reverse engineering. We consider a system with a two-photon driven Kerr nonlinearity, which can generate a pair of dressed even and odd coherent states (i.e., Schrödinger cat states) for fault-tolerant quantum computations. An additional coherent field is applied to linearly drive a cavity mode, to induce oscillations between dressed cat states. By designing this linear drive with invariant-based reverse engineering, we show how to implement nonadiabatic geometric quantum computation with cat qubits. The performance of the protocol is estimated by taking into account the influence of systematic errors, additive white Gaussian noise, 1/f noise, and decoherence including photon loss and dephasing. Numerical results demonstrate that our protocol is robust against these negative factors. Therefore, this protocol may provide a feasible method for nonadiabatic geometric quantum computation in bosonic systems. |
| 18. | Patrycja Tulewicz, Kacper Wrześniewski, Ireneusz Weymann Spintronic transport through a double quantum dot-based spin valve with noncollinear magnetizations Journal of Magnetism and Magnetic Materials, 546 , pp. 168788, 2022. @article{Tulewicz2022, title = {Spintronic transport through a double quantum dot-based spin valve with noncollinear magnetizations}, author = {Patrycja Tulewicz and Kacper Wrześniewski and Ireneusz Weymann}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321010118}, doi = {10.1016/j.jmmm.2021.168788}, year = {2022}, date = {2022-03-15}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {546}, pages = {168788}, abstract = {We study the magnetoresistive properties of a spin valve based on a double quantum dot attached to ferromagnetic leads with noncollinear alignment of magnetic moments. It is assumed that each dot is strongly coupled to its own ferromagnetic electrode, while the hopping between the dots is relatively weak. The calculations are performed by using the perturbation theory in the coupling between the dots, while the local density of states of a quantum dot attached to a given external lead is determined with the aid of the numerical renormalization group method. We demonstrate that the examined device can exhibit considerable positive or inverse tunnel magnetoresistance. It can be also a source of highly spin-polarized current. Importantly, the spin-resolved transport properties can be controlled by gate and bias voltages and depend on the angle between the magnetizations of the ferromagnets.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We study the magnetoresistive properties of a spin valve based on a double quantum dot attached to ferromagnetic leads with noncollinear alignment of magnetic moments. It is assumed that each dot is strongly coupled to its own ferromagnetic electrode, while the hopping between the dots is relatively weak. The calculations are performed by using the perturbation theory in the coupling between the dots, while the local density of states of a quantum dot attached to a given external lead is determined with the aid of the numerical renormalization group method. We demonstrate that the examined device can exhibit considerable positive or inverse tunnel magnetoresistance. It can be also a source of highly spin-polarized current. Importantly, the spin-resolved transport properties can be controlled by gate and bias voltages and depend on the angle between the magnetizations of the ferromagnets. |