# Negative-Mass Hydrodynamics in a Spin-Orbit-Coupled Bose-Einstein Condensate.

@article{Khamehchi2017NegativeMassHI,
title={Negative-Mass Hydrodynamics in a Spin-Orbit-Coupled Bose-Einstein Condensate.},
author={M. A. Khamehchi and Khalid Hossain and Maren E Mossman and Yongping Zhang and Thomas Busch and Michael McNeil Forbes and P. Engels},
journal={Physical review letters},
year={2017},
volume={118 15},
pages={
155301
}
}
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… Expand
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