Control of spin coherence in semiconductor double quantum dots

TL;DR

This paper presents a scheme to control spin coherence in GaAs double quantum dots, achieving significant variations in spin relaxation and dephasing through small gate voltages, with implications for quantum information processing.

Contribution

It introduces a method to manipulate spin coherence in double quantum dots using gate voltages, accounting for multiple decoherence mechanisms with a detailed equation-of-motion approach.

Findings

Up to ten orders of magnitude variation in spin relaxation.

Two orders of magnitude variation in spin dephasing.

Large spin coherence variation persists at 0 K.

Abstract

We propose a scheme to manipulate the spin coherence in vertically coupled GaAs double quantum dots. Up to {\em ten} orders of magnitude variation of the spin relaxation and {\em two} orders of magnitude variation of the spin dephasing can be achieved by a small gate voltage applied vertically on the double dot. Specially, large variation of spin relaxation still exists at 0 K. In the calculation, the equation-of-motion approach is applied to obtain the electron decoherence time and all the relevant spin decoherence mechanisms, such as the spin-orbit coupling together with the electron--bulk-phonon scattering, the direct spin-phonon coupling due to the phonon-induced strain, the hyperfine interaction and the second-order process of electron-phonon scattering combined with the hyperfine interaction, are included. The condition to obtain the large variations of spin coherence is also addressed.