The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Sebastian Diehl - One of the best experts on this subject based on the ideXlab platform.
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keldysh field theory for driven Open Quantum Systems
Reports on Progress in Physics, 2016Co-Authors: Lukas M Sieberer, Michael Buchhold, Sebastian DiehlAbstract:Recent experimental developments in diverse areas-ranging from cold atomic gases to light-driven semiconductors to microcavity arrays-move Systems into the focus which are located on the interface of Quantum optics, many-body physics and statistical mechanics. They share in common that coherent and driven-dissipative Quantum dynamics occur on an equal footing, creating genuine non-equilibrium scenarios without immediate counterpart in equilibrium condensed matter physics. This concerns both their non-thermal stationary states and their many-body time evolution. It is a challenge to theory to identify novel instances of universal emergent macroscopic phenomena, which are tied unambiguously and in an observable way to the microscopic drive conditions. In this review, we discuss some recent results in this direction. Moreover, we provide a systematic introduction to the Open system Keldysh functional integral approach, which is the proper technical tool to accomplish a merger of Quantum optics and many-body physics, and leverages the power of modern Quantum field theory to driven Open Quantum Systems.
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keldysh field theory for driven Open Quantum Systems
arXiv: Quantum Gases, 2015Co-Authors: Lukas M Sieberer, Michael Buchhold, Sebastian DiehlAbstract:Recent experimental developments in diverse areas - ranging from cold atomic gases over light-driven semiconductors to microcavity arrays - move Systems into the focus, which are located on the interface of Quantum optics, many-body physics and statistical mechanics. They share in common that coherent and driven-dissipative Quantum dynamics occur on an equal footing, creating genuine non-equilibrium scenarios without immediate counterpart in condensed matter. This concerns both their non-thermal flux equilibrium states, as well as their many-body time evolution. It is a challenge to theory to identify novel instances of universal emergent macroscopic phenomena, which are tied unambiguously and in an observable way to the microscopic drive conditions. In this review, we discuss some recent results in this direction. Moreover, we provide a systematic introduction to the Open system Keldysh functional integral approach, which is the proper technical tool to accomplish a merger of Quantum optics and many-body physics, and leverages the power of modern Quantum field theory to driven Open Quantum Systems.
Alan Aspuruguzik - One of the best experts on this subject based on the ideXlab platform.
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linear algebraic bath transformation for simulating complex Open Quantum Systems
New Journal of Physics, 2014Co-Authors: Joonsuk Huh, Sarah Mostame, Takatoshi Fujita, Manhong Yung, Alan AspuruguzikAbstract:In studying Open Quantum Systems, the environment is often approximated as a collection of non-interacting harmonic oscillators, a configuration also known as the star-bath model. It is also well known that the star-bath can be transformed into a nearest-neighbor interacting chain of oscillators. The chain-bath model has been widely used in renormalization group approaches. The transformation can be obtained by recursion relations or orthogonal polynomials. Based on a simple linear algebraic approach, we propose a bath partition strategy to reduce the system-bath coupling strength. As a result, the non-interacting star-bath is transformed into a set of weakly coupled multiple parallel chains. The transformed bath model allows complex problems to be practically implemented on Quantum simulators, and it can also be employed in various numerical simulations of Open Quantum dynamics.
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time dependent density functional theory of Open Quantum Systems in the linear response regime
Journal of Chemical Physics, 2011Co-Authors: David G Tempel, Mark A Watson, Roberto Olivaresamaya, Alan AspuruguzikAbstract:Time-dependent density functional theory (TDDFT) has recently been extended to describe many-body Open Quantum Systems evolving under nonunitary dynamics according to a Quantum master equation. In the master equation approach, electronic excitation spectra are broadened and shifted due to relaxation and dephasing of the electronic degrees of freedom by the surrounding environment. In this paper, we develop a formulation of TDDFT linear-response theory (LR-TDDFT) for many-body electronic Systems evolving under a master equation, yielding broadened excitation spectra. This is done by mapping an interacting Open Quantum system onto a noninteracting Open Kohn–Sham system yielding the correct nonequilibrium density evolution. A pseudoeigenvalue equation analogous to the Casida equations of the usual LR-TDDFT is derived for the Redfield master equation, yielding complex energies and Lamb shifts. As a simple demonstration, we calculate the spectrum of a C2 + atom including natural linewidths, by treating the ele...
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time dependent density functional theory for Open Quantum Systems with unitary propagation
Physical Review Letters, 2010Co-Authors: Joel Yuenzhou, David G Tempel, Cesar A Rodriguezrosario, Alan AspuruguzikAbstract:We extend the Runge-Gross theorem for a very general class of Open Quantum Systems under weak assumptions about the nature of the bath and its coupling to the system. We show that for Kohn-Sham (KS) time-dependent density functional theory, it is possible to rigorously include the effects of the environment within a bath functional in the KS potential. A Markovian bath functional inspired by the theory of nonlinear Schrodinger equations is suggested, which can be readily implemented in currently existing real-time codes. Finally, calculations on a helium model system are presented.
Akira Sone - One of the best experts on this subject based on the ideXlab platform.
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Quantum jarzynski equality in Open Quantum Systems from the one time measurement scheme
Physical Review Letters, 2020Co-Authors: Akira Sone, Yixiang Liu, Paola CappellaroAbstract:In Open Quantum Systems, a clear distinction between work and heat is often challenging, and extending the Quantum Jarzynski equality to Systems evolving under general Quantum channels beyond unitality remains an Open problem in Quantum thermodynamics. In this Letter, we introduce well-defined notions of guessed Quantum heat and guessed Quantum work, by exploiting the one-time measurement scheme, which only requires an initial energy measurement on the system alone. We derive a modified Quantum Jarzynski equality and the principle of maximum work with respect to the guessed Quantum work, which requires the knowledge of the system only. We further show the significance of guessed Quantum heat and work by linking them to the problem of Quantum hypothesis testing.
Franco Nori - One of the best experts on this subject based on the ideXlab platform.
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simulating Open Quantum Systems with hamiltonian ensembles and the nonclassicality of the dynamics
Physical Review Letters, 2018Co-Authors: Hong Bin Chen, Clemens Gneiting, Yuehnan Chen, Franco NoriAbstract:The incoherent dynamical properties of Open Quantum Systems are generically attributed to an ongoing correlation between the system and its environment. Here, we propose a novel way to assess the nature of these system-environment correlations by examining the system dynamics alone. Our approach is based on the possibility or impossibility to simulate Open-system dynamics with Hamiltonian ensembles. As we show, such (im)possibility to simulate is closely linked to the system-environment correlations. We thus define the nonclassicality of Open-system dynamics in terms of the nonexistence of a Hamiltonian-ensemble simulation. This classifies any nonunital Open-system dynamics as nonclassical. We give examples for Open-system dynamics that are unital and classical, as well as unital and nonclassical.
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qutip an Open source python framework for the dynamics of Open Quantum Systems
Computer Physics Communications, 2012Co-Authors: J R Johansson, Paul Nation, Franco NoriAbstract:Article history: We present an object-oriented Open-source framework for solving the dynamics of Open Quantum Systems written in Python. Arbitrary Hamiltonians, including time-dependent Systems, may be built up from operators and states defined by a Quantum object class, and then passed on to a choice of master equation or Monte Carlo solvers. We give an overview of the basic structure for the framework before detailing the numerical simulation of Open system dynamics. Several examples are given to illustrate the build up to a complete calculation. Finally, we measure the performance of our library against that of current implementations. The framework described here is particularly well suited to the fields of Quantum optics, superconducting circuit devices, nanomechanics, and trapped ions, while also being ideal for use in classroom instruction.
Paola Cappellaro - One of the best experts on this subject based on the ideXlab platform.
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Quantum jarzynski equality in Open Quantum Systems from the one time measurement scheme
Physical Review Letters, 2020Co-Authors: Akira Sone, Yixiang Liu, Paola CappellaroAbstract:In Open Quantum Systems, a clear distinction between work and heat is often challenging, and extending the Quantum Jarzynski equality to Systems evolving under general Quantum channels beyond unitality remains an Open problem in Quantum thermodynamics. In this Letter, we introduce well-defined notions of guessed Quantum heat and guessed Quantum work, by exploiting the one-time measurement scheme, which only requires an initial energy measurement on the system alone. We derive a modified Quantum Jarzynski equality and the principle of maximum work with respect to the guessed Quantum work, which requires the knowledge of the system only. We further show the significance of guessed Quantum heat and work by linking them to the problem of Quantum hypothesis testing.
