Linear Response of a Periodically Driven Thermal Dipolar Gas

TL;DR

This paper investigates the linear response and normal modes of a periodically driven ultracold dipolar gas, revealing anisotropic effects and unique relaxation behaviors like 'melting modes' using theoretical and numerical methods.

Contribution

It introduces a detailed analysis of the normal modes and linear response of a driven dipolar gas, highlighting anisotropic effects and the discovery of non-oscillatory relaxation modes.

Findings

Resonant response depends on dipole alignment axis.

Identification of 'melting modes' that relax without oscillation.

Use of Monte Carlo and averaging methods for analysis.

Abstract

We study the nonequilibrium dynamics of an ultracold, non-degenerate dipolar gas of $^{164}$Dy atoms in a cylindrically symmetric harmonic trap. To do so, we investigate the normal modes and linear response of the gas when driven by means of periodic modulations to the trap axial-frequency. We find that the resonant response of the gas depends strongly on the dipole alignment axis, owing to anisotropies in the differential cross section of the atoms. We employ the use of the method of averages as well as numerical Monte Carlo methods for our analysis. A striking result is that certain normal modes, termed "melting modes", initiated in an anisotropic out-of-equilibrium configuration, relax to equilibrium without oscillating.