Wave-function approach to dissipative processes in quantum optics

In the preceding paper [Warszawski and Wiseman] we presented a general formalism for determining the state of a quantum system conditional on the output of a realistic detector, including effects such as a finite bandwidth and electronic noise. We applied this theory to two sorts of photodetectors: avalanche photodiodes and photoreceivers. In this paper we present simulations of these realistic quantum trajectories for a cavity QED scenario in order to ascertain how the conditioned state varies from that obtained with perfect detection. Large differences are found, and this is manifest in the average of the conditional purity. Simulation also allows us to comprehensively investigate how the quality of the the photoreceiver depends upon its physical parameters. In particular, we present evidence that in the limit of small electronic noise, the photoreceiver quality can be characterized by an effective bandwidth, which depends upon the level of electronic noise and the filter bandwidth. We establish this result as an appropriate limit for a simpler, analytically solvable, system. We expect this to be a general result in other applications of our theory.

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“…rescence [3,4,5,6]. For this reason, we use it as a test system for investigating realistic photodetection.…”

Section: Introductionmentioning

confidence: 99%

Quantum trajectories for realistic photodetection: II. Application and analysis

Warszawski

Wiseman

2002

J. Opt. B: Quantum Semiclass. Opt.

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“…60,79 Hence, for this situation, the SSE yields the same density matrix dynamics as the KL-ME in eqn (18). There are, however, several interesting features of the SSE that make it attractive compared to the ME, such as its lower numerical cost 80 as well as the novel conceptual insights it provides based on measurement theory.…”

Section: No Proof Yet For the Runge-gross Theorem Analog For Indivmentioning

confidence: 92%

“…[56][57][58][59] The description of OQS is essential in a wide variety of fields, ranging from quantum optics to chemical dynamics in condensed media. [60][61][62][63] In our work on OQS-TDDFT, we have established precise conditions for -V and -A representability for the evolution of general ME. 51,53,93 An interesting outcome of our investigation is that particle and current densities of OQS can be reproduced in closed driven systems (CDS) evolving unitarily.…”

mentioning

confidence: 99%

Remarks on time-dependent [current]-density functional theory for open quantum systems

Yuen-Zhou

Aspuru‐Guzik

2013

Phys. Chem. Chem. Phys.

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Time-dependent [current]-density functional theory for open quantum systems (OQS) has emerged as a formalism that can incorporate dissipative effects in the dynamics of many-body quantum systems.Here, we review and clarify some formal aspects of these theories that have been recently questioned in the literature. In particular, we provide theoretical support for the following conclusions: (1) contrary to what we and others had stated before, within the master equation framework, there is in fact a one-to-one mapping between vector potentials and current densities for fixed initial state, particleparticle interaction, and memory kernel; (2) regardless of the first conclusion, all of our recently suggested Kohn-Sham (KS) schemes to reproduce the current and particle densities of the original OQS, and in particular, the use of a KS closed driven system, remains formally valid; (3) the Lindblad master equation maintains the positivity of the density matrix regardless of the time-dependence of the Hamiltonian or the dissipation operators; (4) within the stochastic Schrödinger equation picture, a one-to-one mapping from stochastic vector potential to stochastic current density for individual trajectories has not been proven so far, except in the case where the vector potential is the same for every member of the ensemble, in which case, it reduces to the Lindblad master equation picture; (5) master equations may violate certain desired properties of the density matrix, such as positivity, but they remain as one of the most useful constructs to study OQS when the environment is not easily incorporated explicitly in the calculation. The conclusions support our previous work as formally rigorous, offer new insights into it, and provide a common ground to discuss related theories.

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“…A method of treating larger systems in the framework of the QME is the stochastic unraveling of QME (also known as quantum jump, quantum trajectory, and Monte Carlo wave function method) [1,2,34,35,36,37,38,39,41,42,40,5,10,11]. In this method, since one treats a wave function instead of a density matrix, one can investigate systems larger than those in the direct methods.…”

Section: Introductionmentioning

confidence: 99%

A Perturbative Method for Nonequilibrium Steady State of Open Quantum Systems

Yuge

Sugita

2015

J. Phys. Soc. Jpn.

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We develop a method of calculating the nonequilibrium steady state (NESS) of an open quantum system that is weakly coupled to reservoirs in different equilibrium states. We describe the system using a Redfield-type quantum master equation (QME). We decompose the Redfield QME into a Lindblad-type QME and the remaining part R. Regarding the steady state of the Lindblad QME as the unperturbed solution, we perform a perturbative calculation with respect to R to obtain the NESS of the Redfield QME. The NESS thus determined is exact up to the first order in the system-reservoir coupling strength (pump/loss rate), which is the same as the order of validity of the QME. An advantage of the proposed method in numerical computation is its applicability to systems larger than those in methods of directly solving the original Redfield QME. We apply the method to a noninteracting fermion system to obtain an analytical expression of the NESS density matrix. We also numerically demonstrate the method in a nonequilibrium quantum spin chain.

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Wave-function approach to dissipative processes in quantum optics

Cited by 1,762 publications

References 28 publications

Quantum trajectories for realistic photodetection: II. Application and analysis

Quantum trajectories for realistic photodetection: II. Application and analysis

Remarks on time-dependent [current]-density functional theory for open quantum systems

A Perturbative Method for Nonequilibrium Steady State of Open Quantum Systems

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