Spinor Dynamics in an Antiferromagnetic spin-1 Thermal Bose Gas
Hyewon K. Pechkis, Jonathan Wrubel, Arne Schwettmann, Paul Griffin, Ryan Barnett, Eite Tiesinga, Paul D. Lett
We present experimental observations of coherent spin-population oscillations in a cold thermal, Bose gas of spin-1 23Na 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 nist-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 in the mF = 0 sublevel after variable times up to a few hundreds of ms. We find quantitative agreement with the measured amplitude and period of the oscillations as a function of magnetic field for different initial conditions and also measure the damping time of the oscillations.