Efficient Measurement of Quantum Gate Error by Interleaved Randomized Benchmarking

TLDR

The authors present a scalable protocol to estimate the average error of individual quantum gates. The method interleaves random Clifford gates around the target gate, uses randomized benchmarking to estimate and bound its average error while accounting for state preparation and measurement errors, and scales with the number of qubits. Applied to a superconducting qubit system, the protocol yields bounded average errors of 0.003 (confidence interval 0–0.016) for single‑qubit X(π/2) and Y(π/2) gates, outperforming estimates from quantum process tomography.

Abstract

We describe a scalable experimental protocol for estimating the average error of individual quantum computational gates. This protocol consists of interleaving random Clifford gates between the gate of interest and provides an estimate as well as theoretical bounds for the average error of the gate under test, so long as the average noise variation over all Clifford gates is small. This technique takes into account both state preparation and measurement errors and is scalable in the number of qubits. We apply this protocol to a superconducting qubit system and find a bounded average error of 0.003 [0,0.016] for the single-qubit gates X(π/2) and Y(π/2). These bounded values provide better estimates of the average error than those extracted via quantum process tomography.