Restricted Thermalization for Two Interacting Atoms in a Multimode Harmonic Waveguide

TL;DR

This study investigates whether two interacting atoms in a multimode harmonic waveguide can reach thermal equilibrium, finding that they do not, even with strong interactions, due to underlying quantum integrability.

Contribution

It demonstrates the failure of thermalization in a two-atom system in a multimode waveguide, linking this to quantum chaos and integrability concepts.

Findings

System shows signatures of quantum chaos but fails to thermalize.

Thermalization is absent even with infinitely strong interactions.

Failure attributed to the system's underlying integrable nature.

Abstract

In this article, we study the thermalizability of a system consisting of two atoms in a circular, transversely harmonic waveguide in the multimode regime. While showing some signatures of the quantum-chaotic behavior, the system fails to reach a thermal equilibrium in a relaxation from an initial state, even when the interaction between the atoms is infinitely strong. We relate this phenomenon to the previously addressed unattainability of a complete quantum chaos in the Seba billiard [P. Seba, Phys. Rev. Lett., 64, 1855 (1990)], and we conjecture the absence of a complete thermalization to be a generic property of integrable quantum systems perturbed by a non-integrable but well localized perturbation.