Benchmarking Gate Fidelities in a Si/SiGe Two-Qubit Device

TL;DR

This paper provides a comprehensive benchmarking of single- and two-qubit gate fidelities in silicon spin qubits, introducing a novel method for more reliable two-qubit fidelity estimation and highlighting progress towards fault-tolerant quantum computing.

Contribution

It introduces character randomized benchmarking for silicon spin qubits, enabling more accurate two-qubit fidelity measurements and addressing cross-talk and error correlations.

Findings

Two-qubit CPhase gate fidelity measured using character randomized benchmarking.

Identification of cross-talk and error correlations in silicon spin qubits.

Progress towards achieving fault-tolerant quantum computation thresholds.

Abstract

We report the first complete characterization of single-qubit and two-qubit gate fidelities in silicon-based spin qubits, including cross-talk and error correlations between the two qubits. To do so, we use a combination of standard randomized benchmarking and a recently introduced method called character randomized benchmarking, which allows for more reliable estimates of the two-qubit fidelity in this system. Interestingly, with character randomized benchmarking, the two-qubit CPhase gate fidelity can be obtained by studying the additional decay induced by interleaving the CPhase gate in a reference sequence of single-qubit gates only. This work sets the stage for further improvements in all the relevant gate fidelities in silicon spin qubits beyond the error threshold for fault-tolerant quantum computation.