Perfect spin filtering device through a Mach Zehnder interferometer in GaAs/AlGaAs electron gas

TL;DR

This paper presents an exact analysis of spin filtering using a Mach-Zehnder interferometer in a 2D electron gas with Rashba and Dresselhaus spin-orbit couplings, proposing feasible experimental conditions for perfect spin polarization.

Contribution

It introduces a fully non-Abelian gauge formulation for spin filtering and identifies two broad solutions, including a purely non-Abelian and an Abelianized approximation, for achieving perfect spin polarization.

Findings

Two broad solutions for perfect spin filtering identified

Filtering achievable for arbitrary incoming polarization

Proposed interferometer setup is experimentally feasible

Abstract

Spin filtering through quantum spin interference is addressed exactly, in two dimensions, in a medium that has both Rashba and Dresselhaus spin-orbit couplings and an applied external magnetic field. The problem is addressed from the fully non-Abelian Gauge formulation. We propose an experimentally feasible electronic Mach Zehnder Interferometer and solve for the perfect spin filtering conditions. We find two broad solutions, one where filtering is achieved in the original incoming basis, that is purely a non-Abelian solution, and the other where one needs a tilted axis to observe the polarized output spinor. The latter solution is well approximated by an Abelianized approximation. Both solutions apply for arbitrary incoming polarization, and are only limited by the randomness of the incoming spinor state.