Spin-orbit signatures in the dynamics of singlet-triplet qubits in double quantum dots

TL;DR

This paper investigates how spin-orbit interaction influences the dynamics of singlet-triplet qubits in double quantum dots, revealing signatures that can be used to measure spin-orbit scales through numerical and analytical methods.

Contribution

It provides a combined numerical and analytical analysis of spin-orbit effects on singlet-triplet qubit dynamics, highlighting measurable signatures in Rabi oscillations.

Findings

Spin-orbit interaction causes frequency shifts in Rabi oscillations.

Fourier amplitude modulation reveals spin-orbit scales.

Signatures originate from interplay between spin-orbit and hyperfine interactions.

Abstract

We characterize numerically and analytically the signatures of the spin-orbit interaction in a two-electron GaAs double quantum dot in the presence of an external magnetic field. In particular, we obtain the return probability of the singlet state by simulating Landau-Zener voltage detuning sweeps which traverse the singlet-triplet ($S-T_+$) resonance. Our results indicate that non-spin-conserving interdot tunneling processes arising from the spin-orbit interaction have well defined signatures. These allow direct access to the spin-orbit interaction scales and are characterized by a frequency shift and Fourier amplitude modulation of the Rabi flopping dynamics of the singlet-triplet qubits $S-T_0$ and $S-T_+$. By applying the Bloch-Feshbach projection formalism, we demonstrate analytically that the aforementioned effects originate from the interplay between spin-orbit interaction and processes driven by the hyperfine interaction between the electron spins and those of the GaAs nuclei.