Observation of the algebraic localization-delocalization transition in a one-dimensional disordered potential with a bias force

Abstract

One-dimensional (1D) Anderson localization phenomena are strongly affected by a bias force or equivalently a voltage in electronic systems. We experimentally study this case, launching a noninteracting ^{39}K Bose-Einstein condensate in a 1D disordered potential induced by a far-off-resonance laser speckle, while controlling a bias force. In agreement with theoretical predictions, we observe a transition between algebraic localization and delocalization as a function of our control parameter that is the relative strength of the disorder against the bias force. We also demonstrate that the transition is intrinsically energy independent and that the initial velocity of the wave packet only plays a role through an effective disorder strength due to the correlation of the disorder.