# Dephasing dynamics of an impurity coupled to an anharmonic environment

## TL;DR

This paper investigates how anharmonic environments influence the dephasing and information back-flow of an impurity, revealing temperature-dependent effects and limitations of Gaussian approximations.

## Contribution

It demonstrates the impact of anharmonicity on dephasing dynamics and non-Markovian behavior, highlighting differences from Gaussian environment assumptions.

## Key findings

- High temperatures cause strong dephasing.
- Low temperatures induce significant information back-flow.
- Gaussian approximation poorly models low-temperature dynamics.

## Abstract

We analyze the dephasing dynamics of an impurity coupled to an anharmonic environment. We show that a strong anharmonicity produces two different effects depending on the environment temperature: for high temperatures, the system suffers a strong dephasing, while for low temperatures there is a strong information back-flow (as measured by the Breuer-Laine-Piilo (BLP) non-Markovianity measure). Both dephasing and back-flow are particularly significant when the anharmonic potential allows environment states very close to the dissociation limit. In contrast, the information back-flow is suppressed when assuming the environment to be Gaussian. In this regard, we find that the Gaussian approximation is particularly poor at low temperatures.