Physical Reduced Stochastic Equations for Continuously Monitored Non-Markovian Quantum Systems with a Markovian Embedding

Fuente: arXiv
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Main Author: Nurdin, Hendra I.
Format: Preprint
Published: 2025
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author Nurdin, Hendra I.
author_facet Nurdin, Hendra I.
contents An effective approach to modeling non-Markovian quantum systems is to embed a principal (quantum) system of interest into a larger quantum system. A widely employed embedding is one that uses another quantum system, referred to as the auxiliary system, which is coupled to the principal system, and both the principal and auxiliary can be coupled to quantum white noise processes. The principal and auxiliary together form a quantum Markov system and the quantum white noises act as a bath (environment) for this system. Recently it was shown that the conditional evolution of the principal system in this embedding under continuous monitoring by a travelling quantum probe can be expressed as a system of coupled stochastic differential equations (SDEs) that involve only operators of the principal system. The reduced conditional state of the principal only (conditioned on the measurement outcomes) is determined by the ``diagonal" blocks of this coupled systems of SDEs. It is shown here that the ``off-diagonal" blocks can be exactly eliminated up to their initial conditions, leaving a reduced closed system of SDEs for the diagonal blocks only. Under additional conditions the off-diagonal initial conditions can be made to vanish. This new closed system of equations, which includes an integration term involving a two-time stochastic kernel, represents the non-Markovian stochastic dynamics of the principal system under continuous-measurement. The system of equations determine the reduced conditional state of the principal only and may be viewed as a stochastic Nakajima-Zwanzig type of equation for continuously monitored non-Markovian quantum systems.
format Preprint
id arxiv_https___arxiv_org_abs_2505_22070
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Physical Reduced Stochastic Equations for Continuously Monitored Non-Markovian Quantum Systems with a Markovian Embedding
Nurdin, Hendra I.
Quantum Physics
Systems and Control
Mathematical Physics
Optimization and Control
An effective approach to modeling non-Markovian quantum systems is to embed a principal (quantum) system of interest into a larger quantum system. A widely employed embedding is one that uses another quantum system, referred to as the auxiliary system, which is coupled to the principal system, and both the principal and auxiliary can be coupled to quantum white noise processes. The principal and auxiliary together form a quantum Markov system and the quantum white noises act as a bath (environment) for this system. Recently it was shown that the conditional evolution of the principal system in this embedding under continuous monitoring by a travelling quantum probe can be expressed as a system of coupled stochastic differential equations (SDEs) that involve only operators of the principal system. The reduced conditional state of the principal only (conditioned on the measurement outcomes) is determined by the ``diagonal" blocks of this coupled systems of SDEs. It is shown here that the ``off-diagonal" blocks can be exactly eliminated up to their initial conditions, leaving a reduced closed system of SDEs for the diagonal blocks only. Under additional conditions the off-diagonal initial conditions can be made to vanish. This new closed system of equations, which includes an integration term involving a two-time stochastic kernel, represents the non-Markovian stochastic dynamics of the principal system under continuous-measurement. The system of equations determine the reduced conditional state of the principal only and may be viewed as a stochastic Nakajima-Zwanzig type of equation for continuously monitored non-Markovian quantum systems.
title Physical Reduced Stochastic Equations for Continuously Monitored Non-Markovian Quantum Systems with a Markovian Embedding
topic Quantum Physics
Systems and Control
Mathematical Physics
Optimization and Control
url https://arxiv.org/abs/2505.22070