Effect of a bias field on disordered waveguides: Universal scaling of conductance and application to ultracold atoms
Résumé
We study the transmission of a disordered waveguide subjected to a finite bias field. The statistical
distribution of transmission is analytically shown to take a universal form. It depends on a single
parameter, the system length expressed in a rescaled metrics, which encapsulates all the microscopic
features of the medium and the bias field. Excellent agreement with numerics is found for various
models of disorder and bias field. For white-noise disorder and a linear bias field, we demonstrate
the algebraic nature of the decay of the transmission with distance, irrespective of the value of
the bias field. It contrasts with the expansion of a wave packet, which features a delocalization
transition for large bias field. The difference is attributed to the different boundary conditions
for the transmission and expansion schemes. The observability of these effects in conductance
measurements for electrons or ultracold atoms is discussed, taking into account key features, such
as finite-range disorder correlations, nonlinear bias fields, and finite temperatures.
Domaines
Gaz Quantiques [cond-mat.quant-gas]
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