Suppression of Hyperfine Dephasing by Spatial Exchange of Double Quantum Dots

TL;DR

This paper proposes a novel method to suppress hyperfine dephasing in double quantum dot spin qubits by adiabatically moving the dots, reducing decoherence with minimal impact from spin-orbit coupling.

Contribution

It introduces a new approach of spatial exchange of quantum dots to mitigate hyperfine-induced decoherence, differing from traditional techniques like spin-echo or polarization.

Findings

Adiabatic dot rotation reduces hyperfine dephasing effectively.

The method achieves infidelity below 10^{-4} after ten cycles.

Spin-orbit effects are smaller than hyperfine interactions in this scheme.

Abstract

We examine the logical qubit system of a pair of electron spins in double quantum dots. Each electron experiences a different hyperfine interaction with the local nuclei of the lattice, leading to a relative phase difference, and thus decoherence. Methods such as nuclei polarization, state narrowing, and spin-echo pulses have been proposed to delay decoherence. Instead we propose to suppress hyperfine dephasing by adiabatic rotation of the dots in real space, leading to the same average hyperfine interaction. We show that the additional effects due to the motion in the presence of spin-orbit coupling are still smaller than the hyperfine interaction, and result in an infidelity below 10^{-4} after ten decoupling cycles. We discuss a possible experimental setup and physical constraints for this proposal.