Giovanni I. Martone, Yun Li, Lev P. Pitaevskii, Sandro Stringari
By calculating the dynamic density response function we identify the excitation spectrum of a Bose-Einstein condensate with equal Rashba and Dresselhaus spin-orbit coupling at zero temperature. The propagation of phonons is strongly affected by the coupling and the velocity of sound vanishes when one approaches the second-order phase transition between the spin polarized and the zero-momentum quantum phases. We also point out the emergence of a roton minimum in the excitation spectrum for small values of the Raman coupling, when one approaches the transition to the stripe phase.
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http://arxiv.org/abs/1207.6804
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