Electrical control of spin relaxation in a quantum dot

TL;DR

This paper demonstrates electrical control over spin relaxation times in a quantum dot by manipulating orbital states, revealing the dominant spin-orbit mediated relaxation mechanism and extracting key parameters like the spin-orbit length.

Contribution

It introduces a method to electrically tune spin relaxation in quantum dots and confirms the theoretical model of spin-orbit mediated relaxation.

Findings

Relaxation rate W varies over an order of magnitude with gate voltages.

Spin-orbit mediated phonon coupling dominates relaxation down to 1 Tesla.

Extracted spin-orbit length matches theoretical predictions.

Abstract

We demonstrate electrical control of the spin relaxation time T_1 between Zeeman split spin states of a single electron in a lateral quantum dot. We find that relaxation is mediated by the spin-orbit interaction, and by manipulating the orbital states of the dot using gate voltages we vary the relaxation rate W= (T_1)^-1 by over an order of magnitude. The dependence of W on orbital confinement agrees with theoretical predictions and from these data we extract the spin-orbit length. We also measure the dependence of W on magnetic field and demonstrate that spin-orbit mediated coupling to phonons is the dominant relaxation mechanism down to 1T, where T_1 exceeds 1s.