Anderson Localization in Degenerate Spin-Orbit Coupled Fermi Gas with Disorder

Abstract

Competition between superconductivity and disorder plays an essential role in understanding the metal-insulator transition. Based on the Bogoliubov-de Gennes framework, we studied an 2D s-wave fermionic optical lattice system with both spin- orbit coupling and disorder are presented. We find that, with the increase of the strength of disorder, the mean superconducting order parameter will vanish while the energy gap will persist, which indicates that the system undergoes a transition from a superconducting state to a gapped insulating state. This can be confirmed by calculating the inverse participation ratio. We also find that, if the strength of disorder is small, the superconducting order parameter and the energy gap will decrease if we increase the strength of spin-orbit coupling and Zeeman field. In the large disorder limits, the increase of the strength of spin- orbit coupling will increase the mean superconducting order parameter. This phenomenon shows that the system is more insensitive to disorder if the spin-orbit coupling is presented. Numerical computing also shows that the whole system breaks up into several superconducting islands instead of being superconductive.

Superfluid-Insulator Transition unambiguously detected by entanglement in one-dimensional disordered superfluids

“…In the regime of strong disorder, the electronic wavefunctions become localized, transforming metals or superconductors in insulators 2 . The latter case – the so-called superfluid to insulator transition (SIT) 3–5 – should be driven either by increasing the disorder strength or by lowering the particle density. The SIT is marked by the decrease of the superfluidity fraction 6 and a distinct non-monotonic behavior of the condensate fraction with disorder intensity 7 .…”

Anderson localization of a spin–orbit coupled Bose–Einstein condensate in disorder potential

“…Anderson transition of attractive fermions are investigated theoretically mainly on lattice systems. [14][15][16] Bose-Einstein condensate (BEC) provides a promising platform in the study of bosons' Anderson localization. One-dimensional interacting BEC expanding in correlated disorder can exhibit Anderson localization.…”