Coherent spin mixing dynamics in thermal $^{87}$Rb spin-1 and spin-2 gases

TL;DR

This paper investigates the non-equilibrium spin mixing dynamics in thermal $^{87}$Rb gases, revealing long-lasting oscillations and magnetic field resonances, modeled effectively by Boltzmann equations, with a confirmed interaction strength increase.

Contribution

It provides the first detailed experimental and theoretical analysis of coherent spin mixing in thermal $^{87}$Rb gases, highlighting the role of enhanced spin-dependent interactions.

Findings

Observation of long-lasting spin population oscillations.

Magnetic field dependent resonance phenomena.

Confirmation of doubled spin-dependent interaction strength.

Abstract

We study the non-equilibrium coherent spin mixing dynamics in ferromagnetic spin-1 and antiferromagnetic spin-2 thermal gases of ultracold $^{87}$Rb atoms. Long lasting spin population oscillations with magnetic field dependent resonances are observed in both cases. Our observations are well reproduced by Boltzmann equations of the Wigner distribution function. Compared to the equation of motion of spinor Bose-Einstein condensates, the only difference here is a factor of two increase in the spin-dependent interaction, which is confirmed directly in the spin-2 case by measuring the relation between the oscillation amplitude and the sample's density.