Metastable states in the planar 2d XY model and dissipation in superfluid flow

TL;DR

This paper investigates superfluid flow stability in the 2D XY model using simulations, exploring metastable states, critical velocities, vortex creation, and comparing theoretical results with experiments.

Contribution

It introduces a simulation-based analysis of superfluid stability, metastable states, and dissipation mechanisms in the 2D XY model, linking theory with experimental observations.

Findings

Superfluidity remains stable in the model under certain conditions.

Critical velocities depend on system geometry and vortex dynamics.

The derived superfluid velocity expression aligns with experimental data.

Abstract

We use the Metropolis algorithm to study the stability of superfluid flow in a model system, namely the two-dimensional planar XY model. Flow properties are examined by studying the behaviour of the system in meta-stable ``twisted'' states. We demonstrate the stability of superfluidity in this model and we discuss the Meissner effect and velocity quantization. We also study the critical velocity and dissipation by vortex creation and rotational flow and their dependence on the geometry of the system. An expression for the average superfluid velocity as a function of time, ${\bar v}_s(t)$, is obtained and compared with experimental results.