Instability of a superfluid Bose gas induced by a locked thermal gas in an optical lattice

TL;DR

This paper investigates how a thermal component locked by an optical lattice can induce instability in a superfluid Bose gas, revealing a thermal-induced instability that aligns with Landau instability predictions.

Contribution

It introduces a dissipative Gross-Pitaevskii model derived from the Bose-Hubbard Hamiltonian to analyze thermal effects on superfluid stability in optical lattices.

Findings

Thermal component locking causes superfluid instability at certain quasi-momenta.

The instability coincides with the Landau instability from the GP equation.

Thermal effects can destabilize superfluid flow in optical lattices.

Abstract

We use a dissipative Gross-Petaevskii equation derived from the Bose-Hubbard Hamiltonian to study the effect of the thermal component on the stability of a current-carrying superfluid state of a Bose gas in an optical lattice potential. We explicitly show that the superfluid state becomes unstable at certain quasi-momentum of the condensate due to a thermal component which is locked by an optical lattice potential. It is shown that this instability coincides with the Landau instability derived from the GP equation.