Superstripes and the excitation spectrum of a spin-orbit-coupled Bose-Einstein condensate

Year: 2013

Authors: Li Y., Martone G.I., Pitaevskii L.P., Stringari S.

Autors Affiliation: University of Trento, INO CNR BEC Center, I-38123 Povo, Italy; Università degli studi di Trento, Dipartimento di Fisica, I-38123 Povo, Italy; Russian Academy of Sciences, Kapitsa Phys Problems Inst, Moscow 119334, Russia

Abstract: Using Bogoliubov theory we calculate the excitation spectrum of a spinor Bose-Einstein condensed gas with an equal Rashba and Dresselhaus spin-orbit coupling in the stripe phase. The emergence of a double gapless band structure is pointed out as a key signature of Bose-Einstein condensation and of the spontaneous breaking of translational invariance symmetry. In the long wavelength limit the lower and upper branches exhibit, respectively, a clear spin and density nature. For wave vectors close to the first Brillouin zone, the lower branch acquires an important density character responsible for the divergent behavior of the structure factor and of the static response function, reflecting the occurrence of crystalline order. The sound velocities are calculated as functions of the Raman coupling for excitations propagating orthogonal and parallel to the stripes. Our predictions provide new perspectives for the identification of supersolid phenomena in ultracold atomic gases.


Volume: 110 (23)      Pages from: 235302  to: 235302

More Information: Useful discussions with G. Shlyapnikov are acknowledged. S. S. likes to thank the hospitality of the Kavli Institute for Theoretical Physics. This work has been supported by ERC through the QGBE grant and by Provincia Autonoma di Trento.
DOI: 10.1103/PhysRevLett.110.235302

Citations: 187
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