Anisotropic dynamics of a spin-orbit-coupled Bose-Einstein condensate

Year: 2012

Authors: Martone GI., Li Y., Pitaevskii LP., Stringari S.

Autors Affiliation: Dipartimento di Fisica, Universita\’ di Trento and INO-CNR BEC Center, I-38123 Povo, Italy; Kapitza Institute for Physical Problems, RAS, Kosygina 2, 119334 Moscow, Russia

Abstract: By calculating the density response function we identify the excitation spectrum of a Bose-Einstein condensate with equal Rashba and Dresselhaus spin-orbit coupling. We find that the velocity of sound along the direction of spin-orbit coupling is deeply quenched and vanishes when one approaches the second-order phase transition between the plane-wave 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, providing the onset of the transition to the stripe phase. Our findings point out the occurrence of a strong anisotropy in the dynamic behavior of the gas. A hydrodynamic description accounting for the collective oscillations in both uniform and harmonically trapped gases is also derived.

Journal/Review: PHYSICAL REVIEW A

Volume: 86 (6)      Pages from: 063621  to: 063621

More Information: Useful discussions with G. Ferrari, G. Lamporesi, T. Ozawa, and I. Spielman are acknowledged. This work has been supported by ERC through the QGBE grant.
DOI: 10.1103/PhysRevA.86.063621

Citations: 122
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