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Published on: March 30, 2017
Spin Rotations in a Bose-Einstein Condensate Driven by Counterflow and Spin-Independent Interactions
David C Spierings1, Joseph H Thywissen1, Aephraim M Steinberg1
1Department of Physics and CQIQC, University of Toronto, Toronto, Ontario M5S 1A7, Canada.
Abstract:
We observe spin rotations caused by atomic collisions in a nonequilibrium Bose-condensed gas of ^{87}Rb. Reflection from a pseudomagnetic barrier creates counterflow in which forward- and backward-propagating matter waves have partly transverse spin directions. Even though inter-atomic interaction strengths are state independent, the indistinguishability of parallel spins leads to spin dynamics. A local magnetodynamic model, which captures the salient features of the observed spin textures, highlights an essential connection between four-wave mixing and collisional spin rotation. The observed phenomenon is commonly thought not to occur in Bose condensates; our observations and model clarify the nature of these effective-magnetic spin rotations.
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