Noise suppression using symmetric exchange gates in spin qubits

TL;DR

This paper demonstrates that using symmetric control for spin-exchange gates in GaAs spin qubits significantly enhances gate quality, primarily by reducing nuclear noise effects, leading to more coherent quantum operations.

Contribution

The study introduces symmetric exchange gating as a superior method over detuning control, achieving up to six times higher gate quality factors in GaAs spin qubits.

Findings

Symmetric gating improves gate quality factor by up to six times.

Decoherence in symmetric exchange is mainly due to nuclear field noise.

Model agrees well with experimental results for noise sources.

Abstract

We demonstrate a substantial improvement in the spin-exchange gate using symmetric control instead of conventional detuning in GaAs spin qubits, up to a factor-of-six increase in the quality factor of the gate. For symmetric operation, nanosecond voltage pulses are applied to the barrier that controls the interdot potential between quantum dots, modulating the exchange interaction while maintaining symmetry between the dots. Excellent agreement is found with a model that separately includes electrical and nuclear noise sources for both detuning and symmetric gating schemes. Unlike exchange control via detuning, the decoherence of symmetric exchange rotations is dominated by rotation-axis fluctuations due to nuclear field noise rather than direct exchange noise.