Propagation of collective pair excitations in disordered Bose superfluids

Samuel Lellouch (1) , Lih-King Lim (1) , Laurent Sanchez-Palencia (1)

1 Laboratoire Charles Fabry / Optique atomique

We study the effect of disorder on the propagation of collective excitations in a disordered Bose superfluid. We incorporate local density depletion induced by strong disorder at the meanfield level, and formulate the transport of the excitations in terms of a screened scattering problem. We show that the competition of disorder, screening, and density depletion induces a strongly non-monotonic energy dependence of the disorder parameter. In three dimensions, it results in a rich localization diagram with four different classes of mobility spectra, characterized by either no or up to three mobility edges. Implications on experiments with disordered ultracold atoms are discussed.

Mots clés: 6785-d; 0570Ln; 0530Jp; 0560Gg

Domaines: Gaz Quantiques [cond-mat.quant-gas]

Samuel Lellouch, Lih-King Lim, Laurent Sanchez-Palencia. Propagation of collective pair excitations in disordered Bose superfluids. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 2015, 92, pp.043611. ⟨hal-01143356⟩