Scalable randomized benchmarking of non-Clifford gates

TL;DR

This paper introduces a scalable randomized benchmarking method for non-Clifford gates in quantum computing, enabling efficient characterization of their average fidelity in multi-qubit systems.

Contribution

It develops a scalable benchmarking procedure for non-Clifford gates, including efficient methods for group element manipulation and circuit synthesis, extending beyond Clifford-only protocols.

Findings

Provides a scalable method for benchmarking non-Clifford gates

Enables efficient sampling and circuit synthesis for large qubit systems

Characterizes average gate fidelity of non-Clifford operations

Abstract

Randomized benchmarking is a widely used experimental technique to characterize the average error of quantum operations. Benchmarking procedures that scale to enable characterization of $n$-qubit circuits rely on efficient procedures for manipulating those circuits and, as such, have been limited to subgroups of the Clifford group. However, universal quantum computers require additional, non-Clifford gates to approximate arbitrary unitary transformations. We define a scalable randomized benchmarking procedure over $n$-qubit unitary matrices that correspond to protected non-Clifford gates for a class of stabilizer codes. We present efficient methods for representing and composing group elements, sampling them uniformly, and synthesizing corresponding $\mathrm{poly}(n)$-sized circuits. The procedure provides experimental access to two independent parameters that together characterize the average gate fidelity of a group element.