Spin-flip phonon-mediated charge relaxation in double quantum dots

TL;DR

This paper provides a theoretical analysis of charge relaxation rates in double quantum dots, focusing on phonon interactions and spin-mixing mechanisms relevant for quantum computing applications.

Contribution

It offers a detailed derivation of phonon density of states and evaluates relaxation rates considering multiple spin-mixing mechanisms in double quantum dots.

Findings

Calculated relaxation rates for different magnetic field regimes.

Identified the roles of piezoelectric and deformation potential couplings.

Analyzed interference effects between spin-mixing mechanisms.

Abstract

We theoretically study the $(1,1)$ triplet to $(0,2)$ singlet relaxation rate in a lateral gate-defined double quantum dot tuned to the regime of Pauli spin blockade. We present a detailed derivation of the effective phonon density of states for this specific charge transition, keeping track of the contribution from piezoelectric as well as deformation potential electron-phonon coupling. We further investigate two different spin-mixing mechanisms which can couple the triplet and singlet states: a magnetic field gradient over the double dot (relevant at low external magnetic field) and spin-orbit interaction (relevant at high field), and we also indicate how the two processes could interfere at intermediate magnetic field. Finally, we show how to combine all results and evaluate the relaxation rate for realistic system parameters.