Scalable fast benchmarking for individual quantum gates with local twirling

Abstract

With the development of controllable quantum systems, fast and practical characterization for multi-qubit gates is essential for building high-fidelity quantum computing devices. The usual way to fulfill this requirement via randomized benchmarking asks for the complicated implementation of numerous multi-qubit twirling gates. How to efficiently and reliably estimate the fidelity of a quantum process remains an open problem. In this work, we propose a character-cycle benchmarking protocol and a character-average benchmarking protocol only using local twirling gates to estimate the process fidelity of an individual multi-qubit operation. Our protocols can characterize a large class of quantum gates including and beyond the Clifford group via the local gauge transformation, which forms a universal gate set for quantum computing. We numerically demonstrate our protocols for a non-Clifford gate -- controlled-$(TX)$ and a Clifford gate -- five-qubit quantum error-correcting encoding circuit. The numerical results show that our protocols can efficiently and reliably characterize the gate process fidelities. Compared with the cross-entropy benchmarking, the simulation results show that the character-average benchmarking achieves three orders of magnitude improvements in terms of sampling complexity.

30 pages, 7 figures

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Cited by in corpus (5)

• Swap Test-based Characterization of Quantum Processes in Universal Quantum Computers
• Linear Cross Entropy Benchmarking with Clifford Circuits
• Group twirling and noise tailoring for multi-qubit controlled phase gates
• Calibrating quantum gates up to 52 qubits in a superconducting processor
• Benchmarking non-Clifford gates using only Pauli twirling group