Collision models in quantum optics

TL;DR

This paper reviews quantum collision models in quantum optics, highlighting their role in studying open quantum systems and non-Markovianity, and clarifies their physical basis through input-output formalism.

Contribution

It provides a comprehensive review of collision models, connecting them with quantum optics formalism and clarifying assumptions about bath correlations and interactions.

Findings

Connection between input-output formalism and collision models

Physical origin of assumptions in collision models

Illustration of collision models in quantum optics scenarios

Abstract

Quantum collision models (CMs) provide advantageous case studies for investigating major issues in open quantum systems theory, and especially quantum non-Markovianity. After reviewing their general definition and distinctive features, we illustrate the emergence of a CM in a familiar quantum optics scenario. This task is carried out by highlighting the close connection between the well-known input-output formalism and CMs. Within this quantum optics framework, usual assumptions in the CMs' literature - such as considering a bath of non-interacting yet initially correlated ancillas - have a clear physical origin.