Spin-orbit coupled particle in a spin bath

TL;DR

This paper studies how spin-orbit coupling affects impurity interactions and spin relaxation in quantum dots, revealing mechanisms for spin decoherence and potential mitigation strategies.

Contribution

It demonstrates that spin-orbit coupling breaks spin conservation in impurity interactions and explores its impact on spin relaxation and decoherence in quantum dot systems.

Findings

Impurity-impurity interactions become non-spin-conserving due to spin-orbit coupling.

Spin relaxation rate in Mn-doped ZnTe quantum dots is approximately 1 microsecond.

Nuclear spin-induced decoherence can still be mitigated by spin echo protocols despite spin-orbit effects.

Abstract

We consider a spin-orbit coupled particle confined in a quantum dot in a bath of impurity spins. We investigate the consequences of spin-orbit coupling on the interactions that the particle mediates in the spin bath. We show that in the presence of spin-orbit coupling, the impurity-impurity interactions are no longer spin-conserving. We quantify the degree of this symmetry breaking and show how it relates to the spin-orbit coupling strength. We identify several ways how the impurity ensemble can in this way relax its spin by coupling to phonons. A typical resulting relaxation rate for a self-assembled Mn-doped ZnTe quantum dot populated by a hole is 1 $\mu$s. We also show that decoherence arising from nuclear spins in lateral quantum dots is still removable by a spin echo protocol, even if the confined electron is spin-orbit coupled.