Effects of boundaries and density inhomogeneity on states of vortex matter in Bose--Einstein condensates at finite temperature

TL;DR

This study investigates how finite size, boundaries, and density inhomogeneity influence the states of vortex matter in trapped Bose--Einstein condensates at finite temperature, using Monte Carlo simulations to explore the persistence of vortex states.

Contribution

It demonstrates that despite inhomogeneity and finite size, distinct vortex matter states can be approximately identified, extending the understanding of vortex behavior in realistic BEC systems.

Findings

Finite size and inhomogeneity do not prevent defining vortex matter states.

Monte Carlo simulations reveal approximate vortex state distinctions in trapped BECs.

Results suggest potential for discovering new vortex states in multi-component BECs.

Abstract

Most of the literature on quantum vortices predicting various states of vortex matter in three dimensions at finite temperatures in quantum fluids is based on an assumption of an extended and homogeneous system. It is well known not to be the case in actual Bose--Einstein condensates in traps which are finite systems with nonuniform density. This raises the question to what extent one can speak of different aggregate states of vortex matter (vortex lattices, liquids and tensionless vortex tangle) in these system. To address this point, in the present work we focus on the finite-size, boundaries and density inhomogeneity effects on thermal vortex matter in a Bose--Einstein condensate. To this end we perform Monte Carlo simulations on a model system describing trapped Bose--Einstein condensates. Throughout the paper, we draw on analogies with results for vortex matter obtained for extended systems. This work suggests that finiteness and intrinsic inhomogeneity of the system not withstanding, one nonetheless can approximately invoke the notion of distinct aggregate states of vortex matter realized at certain length scales. This might be helpful, in particular in search of possible new states of vortex matter in Bose--Einstein condensates with multiple components and different symmetries.