Condensation and vortex formation in Bose-gas upon cooling

TL;DR

This paper investigates how cooling induces vortex formation in a Bose gas transitioning to superfluidity, highlighting the role of critical fluctuations (instantons) and their increasing probability near the transition temperature.

Contribution

It introduces a model linking instanton formation to vortex creation during Bose gas cooling, providing probability calculations in 2D and 3D cases.

Findings

Probability of instanton formation increases near the transition temperature.

Vortex formation is essential for the evolution of instantons in superfluid transition.

Critical fluctuations play a key role in the phase transition process.

Abstract

The mechanism for the transition of a Bose gas to the superfluid state via thermal fluctuations is considered. It is shown that in the process of external cooling some critical fluctuations (instantons) are formed above the critical temperature. The probability of the instanton formation is calculated in the three and two-dimensional cases. It is found that this probability increases as the system approaches the transition temperature. It is shown that the evolution of an individual instanton is impossible without the formation of vortices in its superfluid part.