Anisotropy-driven transition from collisionless to collisional regime in the dipolar modes of a trapped gaseous mixture

TL;DR

This paper investigates how increasing trap anisotropy in a fermion-boson mixture causes a transition from collisionless to collisional dipolar oscillations, revealing anisotropy as a key control parameter.

Contribution

It demonstrates that trap anisotropy induces a transition in dipolar mode behavior from collisionless to collisional regimes in a fermion-boson mixture.

Findings

Anisotropy causes different collision behaviors in oscillations along different directions.

Transition from collisionless to collisional regime occurs as trap becomes more elongated.

Dipolar modes are sensitive to trap geometry and interaction effects.

Abstract

We evaluate the dipolar oscillations of a harmonically trapped fermion gas containing thermal bosonic impurities as a function of the anisotropy of the trap, from the numerical solution of the Vlasov-Landau equations for the one-body phase-space distribution functions. Starting from a situation in which the two components of the gaseous mixture perform almost independent oscillations inside a spherical trap, we demonstrate that different collision behaviors arise for oscillations in different directions as the trap is deformed into an elongated cigar-like shape. An increase in the anisotropy of the confinement thus suffices to drive a transition of dipolar modes from a collisionless to a collisional regime.