Entropy dynamics of a dephasing model in a squeezed thermal bath

TL;DR

This paper investigates the entropy evolution of a two-level quantum system interacting with a squeezed thermal bath, revealing phase-dependent dephasing rates and exact solutions that challenge common approximations.

Contribution

It provides an exact solution for the entropy dynamics in a dephasing model with a squeezed thermal bath, highlighting phase effects not captured by standard approximations.

Findings

Entropy increases monotonically at zero and high temperatures.

Dephasing rate depends on the squeezing phase of the bath.

Standard Born-Markovian approximation cannot capture phase dependence.

Abstract

We study the entropy dynamics of a dephasing model, where a two-level system (TLS) is coupled with a squeezed thermal bath via non-demolition interaction. This model is exactly solvable, and the time dependent states of both the TLS and its bath can be obtained exactly. Based on these states, we calculate the entropy dynamics of both the TLS and the bath, and find that the dephasing rate of the system relies on the squeezing phase of the bath. In zero temperature and high temperature limits, we prove that both the system and bath entropy increases monotonically. Moreover, we find that the dephasing rate of the system relies on the squeezing phase of the bath, and this phase dependence cannot be precisely derived from the Born-Markovian approximation which is widely adopted in open quantum systems.