Simultaneous Spin-Charge Relaxation in Double Quantum Dots

TL;DR

This paper studies how phonon interactions cause spin and charge relaxation in double quantum dots, revealing a non-monotonic dependence on detuning and identifying spin-orbit phonon relaxation as dominant.

Contribution

It introduces a simple model combining direct and indirect decay pathways, validated by experiments, to explain detuning-dependent spin relaxation in double quantum dots.

Findings

Relaxation rate varies non-monotonically with detuning.

Electrical tuning of relaxation rate over several orders of magnitude.

Spin-orbit phonon relaxation is the dominant mechanism.

Abstract

We investigate phonon-induced spin and charge relaxation mediated by spin-orbit and hyperfine interactions for a single electron confined within a double quantum dot. A simple toy model incorporating both direct decay to the ground state of the double dot and indirect decay via an intermediate excited state yields an electron spin relaxation rate that varies non-monotonically with the detuning between the dots. We confirm this model with experiments performed on a GaAs double dot, demonstrating that the relaxation rate exhibits the expected detuning dependence and can be electrically tuned over several orders of magnitude. Our analysis suggests that spin-orbit mediated relaxation via phonons serves as the dominant mechanism through which the double-dot electron spin-flip rate varies with detuning.