Spin Manipulation and Relaxation in Spin-Orbit Qubits

TL;DR

This paper develops a comprehensive theoretical framework for spin manipulation and relaxation in spin-orbit qubits, predicting nonlinear Rabi frequency behavior, deriving anisotropic g-tensors, and calculating relaxation rates relevant to experimental quantum dot systems.

Contribution

It introduces a generalized EDSR Hamiltonian for single and double quantum dots, accounting for arbitrary magnetic fields and spin-orbit interactions, and provides microscopic expressions for g-tensors and relaxation rates.

Findings

Nonlinear Rabi frequency dependence on magnetic field at high Zeeman energies.

Microscopic expression for anisotropic electron g-tensor.

Calculated two-electron-spin relaxation rates due to phonon emission.

Abstract

We derive a generalized form of the Electric Dipole Spin Resonance (EDSR) Hamiltonian in the presence of the spin-orbit interaction for single spins in an elliptic quantum dot (QD) subject to an arbitrary (in both direction and magnitude) applied magnetic field. We predict a nonlinear behavior of the Rabi frequency as a function of the magnetic field for sufficiently large Zeeman energies, and present a microscopic expression for the anisotropic electron g-tensor. Similarly, an EDSR Hamiltonian is devised for two spins confined in a double quantum dot (DQD), where coherent Rabi oscillations between the singlet and triplet states are induced by jittering the inter-dot distance at the resonance frequency. Finally, we calculate two-electron-spin relaxation rates due to phonon emission, for both in-plane and perpendicular magnetic fields. Our results have immediate applications to current EDSR experiments on nanowire QDs, g-factor optimization of confined carriers, and spin decay measurements in DQD spin-orbit qubits.