Critical Velocities for Energy Dissipation from Periodic Motions of Impurity in Bose-Einstein Condensates

TL;DR

This paper investigates the critical velocities at which energy dissipation begins in Bose-Einstein condensates due to impurity motion, revealing that these velocities can be lower than traditional Landau predictions, especially in homogeneous systems.

Contribution

It introduces a microscopic model for impurity motion in BECs that explains lower-than-expected critical velocities without vortices, challenging existing Landau criteria.

Findings

Critical velocities are lower than Landau's prediction.

Energy dissipation occurs at smaller velocities in homogeneous condensates.

Reevaluation of the Landau criterion in absence of vortices.

Abstract

A phenomenon of energy dissipation in Bose-Einstein condensates is studied based on a microscopic model for the motion of impurity. Critical velocities for onset of energy dissipation are obtained for periodic motions, such as a dipole-like oscillation and a circular motion. The first example is similar to a series of MIT group experiments settings where the critical velocity was observed much below the Landau critical velocity. The appearance of the smaller values for the critical velocity is also found in our model, even in the homogeneous condensate in the thermodynamic limit. This suggests that the landau criterion be reexamined in the absence of quantized vortices in the bulk limit.