scholarly journals Loss, Gain, and Singular Points in Open Quantum Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Hichem Eleuch ◽  
Ingrid Rotter
Keyword(s):  
Parameter Space ◽  
Critical Points ◽  
Quantum Physics ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Experimental Results ◽  
Open Quantum ◽  
Exceptional Points ◽  
Complex Eigenvalues ◽  
Dynamical Properties

Non-Hermitian quantum physics is used successfully for the description of different puzzling experimental results, which are observed in open quantum systems. Mostly, the influence of exceptional points on the dynamical properties of the system is studied. At these points, two complex eigenvalues Ei≡Ei+iΓi/2 of the non-Hermitian Hamiltonian H coalesce (where Ei is the energy and Γi is the inverse lifetime of the state i). We show that also the eigenfunctions Φi of the two states play an important role, sometimes even the dominant one. Besides exceptional points, other critical points exist in non-Hermitian quantum physics. At these points a=acr in the parameter space, the biorthogonal eigenfunctions of H become orthogonal. For illustration, we show characteristic numerical results.

Thermodynamics and Control of Open Quantum Systems

2021 ◽  
Author(s):  
Gershon Kurizki ◽  
Abraham G. Kofman
Keyword(s):  
Quantum Chemistry ◽  
Quantum Physics ◽  
Open Quantum Systems ◽  
Condensed Matter ◽  
Quantum Systems ◽  
Open Quantum ◽  
Heat Engines ◽  
Chemistry Research ◽  
And Control ◽  
Quantum Thermodynamic

The control of open quantum systems and their associated quantum thermodynamic properties is a topic of growing importance in modern quantum physics and quantum chemistry research. This unique and self-contained book presents a unifying perspective of such open quantum systems, first describing the fundamental theory behind these formidably complex systems, before introducing the models and techniques that are employed to control their quantum thermodynamics processes. A detailed discussion of real quantum devices is also covered, including quantum heat engines and quantum refrigerators. The theory of open quantum systems is developed pedagogically, from first principles, and the book is accessible to graduate students and researchers working in atomic physics, quantum information, condensed matter physics, and quantum chemistry.

scholarly journals IBM Q Experience as a versatile experimental testbed for simulating open quantum systems

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Guillermo García-Pérez ◽  
Matteo A. C. Rossi ◽  
Sabrina Maniscalco
Keyword(s):  
Quantum Electrodynamics ◽  
Quantum Physics ◽  
Open Quantum Systems ◽  
Cavity Quantum Electrodynamics ◽  
Quantum Systems ◽  
Entangled State ◽  
Specific Class ◽  
Linear Optics ◽  
Open Quantum ◽  
State Generation

AbstractThe advent of noisy intermediate-scale quantum (NISQ) technology is changing rapidly the landscape and modality of research in quantum physics. NISQ devices, such as the IBM Q Experience, have very recently proven their capability as experimental platforms accessible to everyone around the globe. Until now, IBM Q Experience processors have mostly been used for quantum computation and simulation of closed systems. Here, we show that these devices are also able to implement a great variety of paradigmatic open quantum systems models, hence providing a robust and flexible testbed for open quantum systems theory. During the last decade an increasing number of experiments have successfully tackled the task of simulating open quantum systems in different platforms, from linear optics to trapped ions, from nuclear magnetic resonance (NMR) to cavity quantum electrodynamics. Generally, each individual experiment demonstrates a specific open quantum system model, or at most a specific class. Our main result is to prove the great versatility of the IBM Q Experience processors. Indeed, we experimentally implement one and two-qubit open quantum systems, both unital and non-unital dynamics, Markovian and non-Markovian evolutions. Moreover, we realise proof-of-principle reservoir engineering for entangled state generation, demonstrate collisional models, and verify revivals of quantum channel capacity and extractable work, caused by memory effects. All these results are obtained using IBM Q Experience processors publicly available and remotely accessible online.

scholarly journals EXCEPTIONAL POINTS IN OPEN AND PT-SYMMETRIC SYSTEMS

2014 ◽  
Vol 54 (2) ◽  
pp. 106-112 ◽  
Author(s):  
Hichem Eleuch ◽  
Ingrid Rotter
Keyword(s):  
Open Quantum Systems ◽  
Level Density ◽  
Quantum Systems ◽  
Point Of View ◽  
Eigenvalues And Eigenfunctions ◽  
Open Quantum ◽  
Exceptional Points ◽  
Characteristic Features ◽  
High Level ◽  
Symmetric Systems

Exceptional points (EPs) determine the dynamics of open quantum systems and cause also PT symmetry breaking in PT symmetric systems. From a mathematical point of view, this is caused by the fact that the phases of the wavefunctions (eigenfunctions of a non-Hermitian Hamiltonian) relative to one another are not rigid when an EP is approached. The system is therefore able to align with the environment to which it is coupled and, consequently, rigorous changes of the system properties may occur. We compare analytically as well as numerically the eigenvalues and eigenfunctions of a 2 × 2 matrix that is characteristic either of open quantum systems at high level density or of PT symmetric optical lattices. In both cases, the results show clearly the influence of the environment on the system in the neighborhood of EPs. Although the systems are very different from one another, the eigenvalues and eigenfunctions indicate the same characteristic features.

scholarly journals Efficient Exploration of Hamiltonian Parameter Space for Optimal Control of Non-Markovian Open Quantum Systems

2021 ◽  
Vol 126 (20) ◽  
Author(s):  
Gerald E. Fux ◽  
Eoin P. Butler ◽  
Paul R. Eastham ◽  
Brendon W. Lovett ◽  
Jonathan Keeling
Keyword(s):  
Optimal Control ◽  
Parameter Space ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Open Quantum ◽  
Hamiltonian Parameter ◽  
Efficient Exploration

scholarly journals Exceptional Points and Dynamical Phase Transitions

10.14311/1273 ◽  
2010 ◽  
Vol 50 (5) ◽  
Author(s):  
I. Rotter
Keyword(s):  
Phase Transitions ◽  
Quantum Physics ◽  
Open Quantum Systems ◽  
Level Density ◽  
Experimental Studies ◽  
Quantum Systems ◽  
Microwave Cavity ◽  
Exceptional Points ◽  
Dynamical Phase ◽  
Dynamical Phase Transitions

In the framework of non-Hermitian quantum physics, the relation between exceptional points,dynamical phase transitions and the counter intuitive behavior of quantum systems at high level density is considered. The theoretical results obtained for open quantum systems and proven experimentally some years ago on a microwave cavity, may explain environmentally induce deffects (including dynamical phase transitions), which have been observed in various experimental studies. They also agree(qualitatively) with the experimental results reported recently in PT symmetric optical lattices.

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