# Quantum non-Markovian collision models from colored-noise baths

## TL;DR

This paper extends quantum collision models to include colored-noise baths with frequency-dependent coupling, resulting in inherently non-Markovian dynamics demonstrated through an atom-mirror example.

## Contribution

It introduces a generalized collision model framework for non-Markovian quantum dynamics using colored-noise baths, expanding beyond traditional white-noise assumptions.

## Key findings

- Developed a non-Markovian collision model with frequency-dependent coupling.
- Illustrated the model with an atom in front of a mirror showing retardation effects.
- Demonstrated the model's ability to capture non-Markovian behavior.

## Abstract

A quantum collision model (CM), also known as repeated interactions model, can be built from the standard microscopic framework where a system S is coupled to a white-noise bosonic bath under the rotating wave approximation, which typically results in Markovian dynamics. Here, we discuss how to generalize the CM construction to the case of frequency-dependent system-bath coupling, which defines a class of colored-noise baths. This leads to an intrinsically non-Markovian CM, where each ancilla (bath subunit) collides repeatedly with S at different steps. We discuss the illustrative example of an atom in front a mirror in the regime of non-negligible retardation times.