Author(s): M. A. Khamehchi, Khalid Hossain, M. E. Mossman, Yongping Zhang, Th. Busch, Michael McNeil Forbes, and P. Engels
Measurements of an expanding spin-orbit coupled Bose-Einstein condensate indicate that its dispersion features a region of negative effective mass.
[Phys. Rev. Lett. 118, 155301] Published Mon Apr 10, 2017