Bose-Einstein condensation and a two-dimensional walk model

TL;DR

This paper introduces a novel two-dimensional walk model with a phase transition, revealing an exact correspondence with a driven-diffusive system that exhibits Bose-Einstein condensation-like behavior.

Contribution

It presents a new 2D walk model and demonstrates its exact equivalence to a driven-diffusive system undergoing a phase transition, linking it to Bose-Einstein condensation phenomena.

Findings

The walk model exhibits a phase transition.

Partition functions of the walk model and driven-diffusive system are exactly equal.

The driven-diffusive system shows a Bose-Einstein condensation-like phase transition.

Abstract

We introduce a two-dimensional walk model in which a random walker can only move on the first quarter of a two-dimensional plane. We calculate the partition function of this walk model using a transfer matrix method and show that the model undergoes a phase-transition. Surprisingly the partition function of this two-dimensional walk model is exactly equal to that of a driven-diffusive system defined on a discrete lattice with periodic boundary conditions in which a phase transition occurs from a high-density to a low-density phase. The driven-diffusive system can be mapped to a zero-range process where the particles can accumulate in a single lattice site in the low-density phase. This is very reminiscent of real-space Bose-Einstein condensation.