Bogoliubov speed of sound for a dilute Bose-Einstein condensate in a 3d optical lattice
arXiv:cond-mat/0407617 · doi:10.1209/epl/i2004-10140-7
Abstract
We point out that the velocity of propagation of sound wavepackets in a Bose-Einstein condensate filling a three-dimensional cubic optical lattice undergoes a maximum with increasing lattice depth. For a realistic choice of parameters, the maximum sound velocity in a lattice condensate can exceed the sound velocity in a homogeneous condensate with the same average density by 30%. The maximum falls into the superfluid regime, and should be observable under currently achievable laboratory conditions.
6 pages, 2 figures, accepted for publication in Europhys. Lett. http://www.epletters.ch/