Momentum-space signatures of the Anderson transition in a symplectic, two-dimensional, disordered ultracold gas

TL;DR

This paper investigates Anderson localization in a 2D disordered spin-orbit system using momentum-space signatures accessible in ultracold atom experiments, revealing critical properties and unique diffusion behaviors at the metal-insulator transition.

Contribution

It introduces a method to identify the Anderson transition in 2D spin-orbit systems via momentum-space features like CBS and CFS peaks, and measures critical parameters experimentally.

Findings

Critical exponent and mobility edge determined

Anomalous residual diffusion observed at transition

Spin localization in deep localized regime

Abstract

We study Anderson Localization in two dimensional (2D) disordered spin-orbit systems described by the Gaussian symplectic ensemble using momentum-space signatures such as the coherent backscattering (CBS) anti-peak, and the coherent forward scattering (CFS) peak. Significantly, these momentum-space features are readily accessible in ultracold atom experiments through absorption imaging after time-of-flight expansion. The critical exponent and mobility edge of the metal-insulator transition are successfully obtained in this model through a finite-time analysis of the CBS width. An anomalous residual diffusion, unique to 2D, is identified at the transition point where the system changes from a metal to an insulator. A spin localization phenomenon is also observed in the deep localized regime.