Shell-shaped atomic gases

TL;DR

This review explores the unique quantum properties of two-dimensional shell-shaped atomic gases, focusing on phenomena like Bose-Einstein condensation, superfluidity, vortices, and phase transitions in curved geometries.

Contribution

It provides a comprehensive analysis of quantum phenomena in curved shell-shaped gases, highlighting differences from flat superfluids and discussing future experimental prospects.

Findings

Curved geometry influences superfluid and BEC properties.

Vortex behavior differs in spherical versus flat geometries.

Hydrodynamic excitations relate to BKT transition in curved spaces.

Abstract

We review the quantum statistical properties of two-dimensional shell-shaped gases, produced by cooling and confining atomic ensembles in thin hollow shells. We consider both spherical and ellipsoidal shapes, discussing at zero and at finite temperature the phenomena of Bose-Einstein condensation and of superfluidity, the physics of vortices, and the crossover from the Bardeen-Cooper-Schrieffer regime to a Bose-Einstein condensate. The novel aspects associated to the curved geometry are elucidated in comparison with flat two-dimensional superfluids. We also describe the hydrodynamic excitations and their relation with the Berezinskii-Kosterlitz-Thouless transition for two-dimensional flat and curved superfluids. In the next years, shell-shaped atomic gases will be the leading experimental platform for investigations of quantum many-body physics in curved spatial domains.