High fidelity resonant gating of a silicon based quantum dot hybrid qubit

TL;DR

This paper demonstrates high-fidelity, microwave-driven resonant gating of a silicon-based quantum dot hybrid qubit, achieving fast, coherent control with fidelities exceeding 93%, and discusses pathways to surpass 99% fidelity for quantum error correction.

Contribution

First implementation of microwave-driven gate operations on a silicon quantum dot hybrid qubit, significantly reducing charge noise sensitivity and improving gate fidelity.

Findings

Pi rotation time less than 5 ns with >93% fidelity.

Coherence time over 150 ns with dynamic decoupling.

Pathway to >99% gate fidelity for quantum error correction.

Abstract

Isolated spins in semiconductors provide a promising platform to explore quantum mechanical coherence and develop engineered quantum systems. Silicon has attracted great interest as a host material for developing spin qubits because of its weak spin-orbit coupling and hyperfine interaction, and several architectures based on gate defined quantum dots have been proposed and demonstrated experimentally. Recently, a quantum dot hybrid qubit formed by three electrons in double quantum dot was proposed, and non-adiabatic pulsed-gate operation was implemented experimentally, demonstrating simple and fast electrical manipulations of spin states with a promising ratio of coherence time to manipulation time. However, the overall gate fidelity of the pulse-gated hybrid qubit is limited by relatively fast dephasing due to charge noise during one of the two required gate operations. Here we perform the first microwave-driven gate operations of a quantum dot hybrid qubit, avoiding entirely the regime in which it is most sensitive to charge noise. Resonant detuning modulation along with phase control of the microwaves enables a pi rotation time of less than 5 ns (50 ps) around X(Z)-axis with high fidelities > 93 (96) %. We also implement Hahn echo and Carr-Purcell (CP) dynamic decoupling sequences with which we demonstrate a coherence time of over 150 ns. We further discuss a pathway to improve gate fidelity to above 99 %, exceeding the threshold for surface code based quantum error correction.