Equilibration of Non-interacting Photons and Quantum Signatures of Chaos

TL;DR

This paper shows that non-interacting photons can equilibrate due to quantum chaos, with mechanisms involving operator spreading and interference, demonstrated through a photonic implementation of a Floquet system.

Contribution

It establishes a link between quantum chaos and photon equilibration, introducing a photonic setup for the multiparticle kicked rotor as a concrete example.

Findings

Single-particle chaos induces photon equilibration.

Operator spreading and interference are key mechanisms.

Photonic implementation of the multiparticle kicked rotor is feasible.

Abstract

Equilibration plays a fundamental role in our understanding of statistical mechanics and the long-time dynamics of many-body systems. In quantum systems, the route to equilibration is intimately related to level repulsion and quantum signatures of chaos that are encoded in their unitary evolution. Chaotic quantum systems exhibit the level statistics characteristic of ensembles of random matrices. In this work, we demonstrate that single-particle chaos leads to equilibration of many non-interacting photons. We show that the underlying mechanisms for equilibration are operator spreading and quantum interference. More specifically, we demonstrate that the unitary dynamics of a general Floquet system implemented using single-mode phase shifters and multiport beamsplitters leads to equilibration of photons. We propose a realistic photonic implementation of the multiparticle kicked rotor, which is a Floquet system that we use as a concrete example of our general approach.