Single spin qubit geometric gate in a silicon quantum dot

TL;DR

This paper demonstrates a high-fidelity single spin qubit in silicon quantum dots using geometric quantum gates, highlighting their potential for noise-resilient quantum control despite current fidelity limitations.

Contribution

It introduces geometric quantum computing in silicon quantum dots to improve noise resilience and discusses the impact of heating effects on gate fidelity.

Findings

Achieved 99.12% average control fidelity with randomized benchmarking.

Dephasing time T2* is 1.025 microseconds, extended to 264 microseconds with Hahn echo.

Geometric quantum gates show promise but currently have fidelities below 99% due to heating effects.

Abstract

Preserving qubit coherence and maintaining high-fidelity qubit control under complex noise environment is an enduring challenge for scalable quantum computing. Here we demonstrate an addressable fault-tolerant single spin qubit with an average control fidelity of 99.12% via randomized benchmarking on a silicon quantum dot device with an integrated micromagnet. Its dephasing time T2* is 1.025 us and can be enlarged to 264 us by using the Hahn echo technique, reflecting strong low-frequency noise in our system. To break through the noise limitation, we introduce geometric quantum computing to obtain high control fidelity by exploiting its noise-resilient feature. However, the control fidelities of the geometric quantum gates are lower than 99%. According to our simulation, the noise-resilient feature of geometric quantum gates is masked by the heating effect. With further optimization to alleviate the heating effect, geometric quantum computing can be a potential approach to reproducibly achieving high-fidelity qubit control in a complex noise environment.