Weak coupling limit for quantum systems with unbounded weakly commuting system operators

Fuente: arXiv
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Autores principales: Lopatin, Ilya, Pechen, Alexander
Formato: Preprint
Publicado: 2025
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author Lopatin, Ilya
Pechen, Alexander
author_facet Lopatin, Ilya
Pechen, Alexander
contents This work is devoted to a rigorous analysis of the weak coupling limit (WCL) for the reduced dynamics of an open infinite-dimensional quantum system interacting with electromagnetic field or a reservoir formed by Fermi or Bose particles in the dipole approximation. The free system Hamiltonian and the system part of the Hamiltonian describing interaction with the reservoir are considered as unbounded operators with continuous spectrum which are commuting in a weak sense. We derive in the weak coupling limit the reservoir statistics, which is determined by whose terms in the multi-point correlation functions of the reservoir which are non-zero in the WCL. Then we prove that the resulting reduced system dynamics converges to unitary dynamics (such behavior sometimes called as Quantum Cheshire Cat effect) with a modified Hamiltonian which can be interpreted as a Lamb shift to the original Hamiltonian. We obtain exact form of the modified Hamiltonian and estimate the rate of convergence to the limiting dynamics. For Fermi reservoir, we prove the convergence of the full Dyson series. For Bose case the convergence is understood term by term.
format Preprint
id arxiv_https___arxiv_org_abs_2505_08241
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Weak coupling limit for quantum systems with unbounded weakly commuting system operators
Lopatin, Ilya
Pechen, Alexander
Mathematical Physics
Quantum Physics
81S22
This work is devoted to a rigorous analysis of the weak coupling limit (WCL) for the reduced dynamics of an open infinite-dimensional quantum system interacting with electromagnetic field or a reservoir formed by Fermi or Bose particles in the dipole approximation. The free system Hamiltonian and the system part of the Hamiltonian describing interaction with the reservoir are considered as unbounded operators with continuous spectrum which are commuting in a weak sense. We derive in the weak coupling limit the reservoir statistics, which is determined by whose terms in the multi-point correlation functions of the reservoir which are non-zero in the WCL. Then we prove that the resulting reduced system dynamics converges to unitary dynamics (such behavior sometimes called as Quantum Cheshire Cat effect) with a modified Hamiltonian which can be interpreted as a Lamb shift to the original Hamiltonian. We obtain exact form of the modified Hamiltonian and estimate the rate of convergence to the limiting dynamics. For Fermi reservoir, we prove the convergence of the full Dyson series. For Bose case the convergence is understood term by term.
title Weak coupling limit for quantum systems with unbounded weakly commuting system operators
topic Mathematical Physics
Quantum Physics
81S22
url https://arxiv.org/abs/2505.08241