Hydrodynamics of Superfluid Bose Gases in an Optical Lattice at Finite Temperatures

TL;DR

This paper derives generalized hydrodynamic equations for superfluid Bose gases in optical lattices at finite temperatures, revealing how the lattice modifies superfluid stability and the Landau criterion.

Contribution

It introduces a new set of coupled hydrodynamic equations based on an effective action, incorporating finite temperature effects and lattice periodicity.

Findings

Landau instability mechanism analyzed at finite temperatures.

Optical lattice modifies the traditional Landau criterion for superfluidity.

Damping processes between condensate and noncondensate atoms are characterized.

Abstract

Starting from an effective action for the order parameter field, we derive a coupled set of generalized hydrodynamic equations for a Bose condensate in an optical lattice at finite temperatures. Using the linearized hydrodynamic equations, we study the microscopic mechanism of the Landau instability due to the collisional damping process between condensate and noncondensate atoms. It is shown that the Landau criterion of the superfluidity for the uniform system is modified due to the presence of the periodic optical lattice potential.