The short-time and long-time behaviors of non-Markovianity measure using two-time correlation functions in open quantum systems

TL;DR

This paper explores how non-Markovian effects in open quantum systems evolve over time using two-time correlation functions, highlighting the influence of system parameters and environment temperature on memory effects.

Contribution

It introduces a non-Markovianity measure based on two-time correlations that can be experimentally measured and analyzes its behavior across different time scales and conditions.

Findings

Non-Markovianity depends on system-environment coupling and temperature.

Thermal fluctuations reduce non-Markovian memory effects.

Initial state influences non-Markovianity differently over time.

Abstract

We investigate non-Markovianity measure using two-time correlation functions for open quantum systems. We define non-Markovianity measure as the difference between the exact two-time correlation function and the one obtained in the Markov limit. Such non-Markovianity measure can easily be measured in experiments. We found that the non-Markovianity dynamics in different time scale crucially depends on the system-environment coupling strength and other physical parameters such as the initial temperature of the environment and the initial state of the system. In particular, we obtain the short-time and long-time behaviors of non-Markovianity for different spectral densities. We also find that the thermal fluctuation always reduce the non-Markovian memory effect. Also, the non-Markovianity measure shows non-trivial initial state dependence in different time scales.