Negative-Mass Hydrodynamics in a Spin-Orbit–coupled Bose-Einstein Condensate
Description
A negative effective mass can be realized in quantum systems by engineering the dispersion relation. A powerful method is provided by spin-orbit coupling, which is currently at the center of intense research efforts. Here we measure an expanding spin-orbit coupled Bose-Einstein condensate whose dispersion features a region of negative effective mass. We observe a range of dynamical phenomena, including the breaking of parity and of Galilean covariance, dynamical instabilities, and self-trapping. The experimental findings are reproduced by a single-band Gross-Pitaevskii simulation, demonstrating that the emerging features—shock waves, soliton trains, self-trapping, etc.—originate from a modified dispersion. Our work also sheds new light on related phenomena in optical lattices, where the underlying periodic structure often complicates their interpretation.
source:https://link.aps.org/doi/10.1103/PhysRevLett.118.155301
Journal
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- Physical Review Letters
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Physical Review Letters 118 (15), 155301-, 2017-04-10
American Physical Society
