title: Spinor dynamics in an antiferromagnetic spin-1 thermal Bose gas.
abstract: 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 equations, with a factor of 2 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.
authors.affiliation: Quantum Measurement Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899-8424, USA.
authors.forename: H K
authors.initials: HK
authors.lastname: Pechkis
authors.forename: J P
authors.initials: JP
authors.lastname: Wrubel
authors.forename: A
authors.initials: A
authors.lastname: Schwettmann
authors.forename: P F
authors.initials: PF
authors.lastname: Griffin
authors.forename: R
authors.initials: R
authors.lastname: Barnett
authors.forename: E
authors.initials: E
authors.lastname: Tiesinga
authors.forename: P D
authors.initials: PD
authors.lastname: Lett