Unveiling the Markovian to non-Markovian transition with quantum collision models

TL;DR

This paper investigates the transition from Markovian to non-Markovian dynamics in open quantum systems using collision models, revealing how information backflows depend on system-ancilla interactions and bath size.

Contribution

It introduces a collision model framework to analyze the Markovian to non-Markovian transition, highlighting the role of ancilla interactions and bath size in information backflows.

Findings

Information backflows show chaotic and regular oscillations depending on interaction probabilities.

Adding more ancillas reduces information backflows, indicating a transition towards Markovian behavior.

Single-ancilla dynamics exhibit complex oscillatory behavior influenced by interaction parameters.

Abstract

The concept of non-Markovianity in open quantum systems is traditionally associated with the existence of information backflows from the environment to the system. Meanwhile, the mechanisms through which such backflows emerge are still a subject of debate. In this work, we use collision models to study memory effects in the dynamics of a qubit system in contact with a thermal bath made up of few ancillas, in which system-ancilla and ancilla-ancilla interactions are considered. In the single-ancilla limit case, we show that the system-bath information flow exhibits an interesting mixture of chaotic and regular oscillatory behavior, which depends on the interaction probabilities. In parallel, our results clearly indicate that the information backflows decrease when new ancillas are added to the bath, which sheds light on the nature of the Markovian to non-Markovian transition.