Two-time correlation functions beyond quantum regression theorem: Effect of external noise

TL;DR

This paper investigates two-time correlation functions in a driven two-level system beyond the quantum regression theorem, revealing how external noise influences system dynamics and spectral properties.

Contribution

It introduces corrections beyond the quantum regression theorem for two-time correlations and explores noise effects on spectral and dynamical behaviors in strong coupling regimes.

Findings

External noise can be tuned to control correlation corrections at low temperatures.

Motional averaging and narrowing effects influence absorption and emission spectra.

External noise impacts tunneling and transport phenomena in the system.

Abstract

We present the results of a study of the two-time correlation functions of a dichotomously driven two-level system in contact with a thermal bath by using corrections beyond the quantum regression theorem. In the strong system-environment coupling regime, it is found that the noise parameters could be tuned to control the magnitude of corrections at low environmental temperatures. The motional averaging and narrowing effect of the external noise was observed on the absorption and emission spectra of the two-state system. Furthermore, effects similar to the destruction of tunneling and noise enhancement of transport are observed in the dynamics of the two-time correlations.