Vortex lattices of bosons in deep rotating optical lattices

TL;DR

This paper investigates vortex lattice phases in a rotating Bose gas within optical lattices near the superfluid-Mott insulator transition, revealing structural phase transitions and connections to the Hofstadter butterfly spectrum.

Contribution

It introduces a detailed analysis of vortex structures and phase transitions in rotating optical lattices close to the superfluid-Mott insulator boundary, linking vortex pinning to spectral properties.

Findings

Vortex lattices exhibit abrupt structural phase transitions.

Vortices are pinned either on plaquettes or on sites.

Connections to the Hofstadter butterfly spectrum are established.

Abstract

We study vortex-lattice phases for a Bose gas trapped in a rotating optical-lattice near the superfluid--Mott-insulator transition. We find a series of abrupt structural phase transitions where vortices are pinned with their cores only on plaquettes or only on sites. We discuss connections between these vortex structures and the Hofstadter-butterfly spectrum of free particles on a rotating lattice.