@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}
}

@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}
}

@article{Kalaga2021,
title = {Violation of Leggett–Garg Inequalities in a Kerr-Type Chaotic System},
author = {Joanna K. Kalaga and Anna Kowalewska-Kudłaszyk and Mateusz Nowotarski and Wiesław Leoński},
url = {https://doi.org/10.3390/photonics8010020},
doi = {10.3390/photonics8010020},
year = {2021},
date = {2021-01-12},
journal = {Photonics},
volume = {8},
number = {1},
pages = {20},
publisher = {MDPI AG},
abstract = {We consider a quantum nonlinear Kerr-like oscillator externally pumped by a series of ultrashort coherent pulses to analyze the quantum time-correlations appearing while the system evolves. For that purpose, we examine the violation of the Leggett–Garg inequality.
We show how the character of such correlations changes when the system’s dynamics correspond to the regular and chaotic regions of its classical counterpart.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}