Spin polarization via decoherence in spin-orbit active media coupled to an electron reservoir

TL;DR

This paper demonstrates how decoherence introduced via an electron reservoir in a spin-orbit active medium can generate and control electron spin polarization, achieving up to 80% polarization in a four-probe setup.

Contribution

It introduces a novel method of inducing and modulating electron spin polarization through controlled decoherence in a spin-orbit coupled system.

Findings

Decoherence via an electron reservoir can produce significant spin polarization.

Spin polarization up to 80% is achievable with realistic spin-orbit strengths.

Symmetric roles of Rashba and Dresselhaus interactions in polarization control.

Abstract

We study the spin polarization of mixed and entangled electron states in a four probe/beam splitter geometry with local Rashba and Dresselhaus interactions. A pair of maximally entangled electrons collides with the beam splitter and enters into two perpendicular branches of length L, composed of spin-orbit active materials (gate confined 2D electron gas). One of the branches is connected to an electron reservoir that acts as a source of decoherence by either behaving as a voltage probe or as a controlled source or sink of current at fixed voltage. Such decoherence source is used to modify the entropy of an unpolarized incoming state in order to generate electron polarization at one or both output branches. The degree of entanglement of the global state and the spin polarization is computed for the outgoing electrons as a function of the coupling to the electron reservoir. Experimentally available spin-orbit strength at the beam splitter arms, for arm lengths of a few micrometers, is able to modulate spin polarization up to 80% in particular spin axes proportional to the decoherence current. The Dresselhaus and Rashba coefficients play a symmetric role in modulating the polarization. Significantly less polarization is achieved for incoming mixed states due to the local operation of the reservoir.