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.

Keywords: 6785-d; 0570Ln; 0530Jp; 0560Gg

Domains: Physics [physics]; Condensed Matter [cond-mat]; Quantum Gases [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, 2015, 92, pp.043611. ⟨hal-01143356⟩