On the effect of repulsive interactions on Bose-Einstein condensation in the Luttinger-Sy model

TL;DR

This paper examines how repulsive interactions influence Bose-Einstein condensation in a one-dimensional disordered system, showing that strong repulsion prevents macroscopic occupation of eigenstates.

Contribution

It provides rigorous results on the suppression of Bose-Einstein condensation due to strong repulsive interactions in the Luttinger-Sy model.

Findings

Strong repulsive interactions prevent macroscopic occupation of eigenstates.

Both hard core and general repulsive interactions lead to suppression of condensation.

Results hold for a range of interaction parameters in the thermodynamic limit.

Abstract

In this paper we investigate the effect of repulsive pair interactions on Bose-Einstein condensation in a well-established random one-dimensional system known as the Luttinger-Sy model at positive temperature. We study separately hard core interactions as well as a class of more general repulsive interactions, also allowing for a scaling of certain interaction parameters in the thermodynamic limit. As a main result, we prove in both cases that for sufficiently strong interactions all eigenstates of the non-interacting one-particle Luttinger-Sy Hamiltonian as well as any sufficiently localized one-particle state are almost surely not macroscopically occupied.