Controlling Decoherence of Transported Quantum Spin Information in Semiconductor Spintronics

TL;DR

This paper examines how to maintain quantum coherence of electron spins in semiconductor spintronic devices by analyzing spin transport and decoherence mechanisms using quantum transport techniques.

Contribution

It introduces a method to quantify spin coherence decay during transport by analyzing the spin density matrix from the Landauer transmission matrix.

Findings

Decoherence arises from spin-orbit interactions and scattering.

Quantum interference effects can be preserved in ballistic and non-ballistic devices.

The approach helps identify conditions for maintaining spin coherence.

Abstract

We investigate quantum coherence of electron spin transported through a semiconductor spintronic device, where spins are envisaged to be controlled by electrical means via spin-orbit interactions. To quantify the degree of spin coherence, which can be diminished by an intrinsic mechanism where spin and orbital degrees of freedom become entangled in the course of transport involving spin-orbit interaction and scattering, we study the decay of the off-diagonal elements of the spin density matrix extracted directly from the Landauer transmission matrix of quantum transport. This technique is applied to understand how to preserve quantum interference effects of fragile superpositions of spin states in ballistic and non-ballistic multichannel semiconductor spintronic devices.