Bose gas: Theory and Experiment

TL;DR

This paper reviews the physics of superfluid helium and Bose-Einstein condensates in dilute gases, discussing theoretical concepts, experimental techniques, and recent advances in creating synthetic gauge fields and vortices.

Contribution

It provides a comprehensive overview of BEC theory, experimental methods, and recent developments in synthetic gauge fields and exotic condensates.

Findings

Laser coupling fields can mimic rotation effects in BECs.

Synthetic gauge fields induce vortices without physical rotation.

Recent experiments demonstrate complex condensate behaviors.

Abstract

For many years, $^4$He typified Bose-Einstein superfluids, but recent advances in dilute ultra-cold alkali-metal gases have provided new neutral superfluids that are particularly tractable because the system is dilute. This chapter starts with a brief review of the physics of superfluid $^4$He, followed by the basic ideas of Bose-Einstein condensation (BEC), first for an ideal Bose gas and then considering the effect of interparticle interactions, including time-dependent phenomena. Extensions to more exotic condensates include magnetic dipolar gases, mixtures of two components, and spinor condensates that require a focused infrared laser for trapping of all the various hyperfine magnetic states in a particular hyperfine $F$ manifold of $m_F$ states. With an applied rotation, the trapped BECs nucleate quantized vortices. Recent theory and experiment have shown that laser coupling fields can mimic the effect of rotation. The resulting synthetic gauge fields have produced vortices in a nonrotating condensate.