Spinor dynamics in an antiferromagnetic spin-1 thermal Bose gas

TL;DR

This paper reports the observation of coherent spin-population oscillations in a thermal Bose gas of sodium-23 atoms, showing similar behavior to condensates and providing a theoretical framework for understanding these dynamics.

Contribution

It demonstrates that thermal spin-1 Bose gases exhibit spin dynamics analogous to condensates, with a modified interaction coefficient, supported by experimental measurements and theoretical analysis.

Findings

Spin-population oscillations observed in thermal gas match condensate behavior.

Theoretical model with a modified interaction coefficient explains the observations.

Quantitative agreement between theory and experiment for oscillation amplitude and period.

Abstract

We present experimental observations of coherent spin-population oscillations in a cold thermal, Bose gas of spin-1 sodium-23 atoms. The population oscillations in a multi-spatial-mode thermal gas have the same behavior as those observed in a single-spatial-mode antiferromagnetic spinor Bose Einstein condensate. We demonstrate this by showing that the two situations are described by the same dynamical equations, with a factor of two change in the spin-dependent interaction coefficient, which results from the change to particles with distinguishable momentum states in the thermal gas. We compare this theory to the measured spin population evolution after times up to a few hundreds of ms, finding quantitative agreement with the amplitude and period. We also measure the damping time of the oscillations as a function of magnetic field.