Transition to hydrodynamics in colliding fermion clouds

TL;DR

This paper investigates how a two-component fermion gas transitions from collisionless to hydrodynamic behavior by analyzing dipolar oscillations, revealing temperature-dependent shifts in the transition point.

Contribution

It provides a detailed numerical study of the transition dynamics in fermionic mixtures using Vlasov-Landau equations, highlighting mode-dependent behaviors.

Findings

Transition to hydrodynamics occurs at lower collision rates as temperature decreases.

Dipolar oscillation frequencies exhibit master/slave behavior depending on the mode.

The transition point varies with initial conditions and mode excitation.

Abstract

We study the transition from the collisionless to the hydrodynamic regime in a two-component spin-polarized mixture of 40K atoms by exciting its dipolar oscillation modes inside harmonic traps. The time evolution of the mixture is described by the Vlasov-Landau equations and numerically solved with a fully three-dimensional concurrent code. We observe a master/slave behaviour of the oscillation frequencies depending on the dipolar mode that is excited. Regardless of the initial conditions, the transition to hydrodynamics is found to shift to lower values of the collision rate as temperature decreases.