Commensurate-incommensurate transition of cold atoms in an optical lattice

TL;DR

This paper investigates the phase transition of cold atoms in an optical lattice, focusing on the superfluid to Mott insulator transition and the effects of one-dimensional confinement on atom pinning.

Contribution

It derives the phase diagram for atom pinning in one-dimensional strongly interacting gases under a periodic potential.

Findings

Identification of the phase boundary for the transition.

Detection methods via excitation gap and Bragg peaks.

Analysis of pinning instability in one-dimensional gases.

Abstract

An atomic gas subject to a commensurate periodic potential generated by an optical lattice undergoes a superfluid--Mott insulator transition. Confining a strongly interacting gas to one dimension generates an instability where an arbitrary weak potential is sufficient to pin the atoms into the Mott state; here, we derive the corresponding phase diagram. The commensurate pinned state may be detected via its finite excitation gap and the Bragg peaks in the static structure factor.