Confinement to deterministic manifolds and low-dimensional solution formulas for continuously measured quantum systems

Fuente: arXiv
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Auteurs principaux: Sarlette, Alain, Elouard, Cyril, Rouchon, Pierre
Format: Preprint
Publié: 2025
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author Sarlette, Alain
Elouard, Cyril
Rouchon, Pierre
author_facet Sarlette, Alain
Elouard, Cyril
Rouchon, Pierre
contents Quantum systems subjected to a continuous weak measurement process evolve according to stochastic differential equations (SDE). Depending on the outcomes of these stochastic measurements, the quantum state may diffuse in various directions across the state space. This note points out that in many scenarios relevant to quantum engineering, this diffusion is effectively constrained to a low-dimensional space. Specifically, the quantum state remains confined to a low-dimensional, nonlinear manifold -- often time-dependent, yet independent of the specific measurement outcomes. This note derives the corresponding low-dimensional formulations for expressing the stochastically evolving state in several prototypical cases: quantum non-demolition measurements in arbitrary dimensions; quadrature measurements of a harmonic oscillator (linear quantum system); and measurements of subsystems within multipartite quantum systems. Additionally, it introduces an algebraic criterion to determine whether such low-dimensional manifolds exist or persist when additional dynamics are present.
format Preprint
id arxiv_https___arxiv_org_abs_2503_08296
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Confinement to deterministic manifolds and low-dimensional solution formulas for continuously measured quantum systems
Sarlette, Alain
Elouard, Cyril
Rouchon, Pierre
Quantum Physics
Quantum systems subjected to a continuous weak measurement process evolve according to stochastic differential equations (SDE). Depending on the outcomes of these stochastic measurements, the quantum state may diffuse in various directions across the state space. This note points out that in many scenarios relevant to quantum engineering, this diffusion is effectively constrained to a low-dimensional space. Specifically, the quantum state remains confined to a low-dimensional, nonlinear manifold -- often time-dependent, yet independent of the specific measurement outcomes. This note derives the corresponding low-dimensional formulations for expressing the stochastically evolving state in several prototypical cases: quantum non-demolition measurements in arbitrary dimensions; quadrature measurements of a harmonic oscillator (linear quantum system); and measurements of subsystems within multipartite quantum systems. Additionally, it introduces an algebraic criterion to determine whether such low-dimensional manifolds exist or persist when additional dynamics are present.
title Confinement to deterministic manifolds and low-dimensional solution formulas for continuously measured quantum systems
topic Quantum Physics
url https://arxiv.org/abs/2503.08296