Two-dimensional Bose gas under extreme rotation

TL;DR

This paper investigates a 2D Bose gas under extreme rotation, revealing a transition from a quantum fluid with a roton-maxon spectrum to a vortex lattice state as interaction strength increases.

Contribution

It introduces the formation of a novel elongated quantum fluid with a roton-maxon spectrum and describes the transition to a vortex lattice at high interaction strengths.

Findings

Roton energy reaches zero at a critical interaction strength.

Transition to a vortex lattice occurs via a second order quantum phase transition.

Vortices form a triangular Abrikosov lattice at high interactions.

Abstract

We show that a Bose-condensed gas under extreme rotation in a 2D anisotropic trap, forms a novel elongated quantum fluid which has a roton-maxon excitation spectrum. For a sufficiently large interaction strength, the roton energy reaches zero and the system undergoes a second order quantum transition to the state with a periodic structure - rows of vortices. The number of rows increases with the interaction, and the vortices eventually form a triangular Abrikosov lattice.