Validating quantum computers using randomized model circuits

TLDR

Quantum volume is a pragmatic metric for comparing progress toward lower system‑wide gate error rates in near‑term quantum computation and error‑correction experiments. The authors introduce quantum volume as a single‑number metric that can be measured on modest‑size quantum computers (n≲50) and report values up to 16 on state‑of‑the‑art transmon devices. Quantum volume is defined as the largest width‑equal‑depth random circuit that a device can successfully implement, measured via a concrete protocol on near‑term hardware. Quantum volume correlates with system error rates and is reduced by uncontrolled interactions, while high‑fidelity operations, connectivity, large calibrated gate sets, and circuit‑rewriting toolchains are expected to yield higher volumes.

Abstract

We introduce a single-number metric, quantum volume, that can be measured using a concrete protocol on near-term quantum computers of modest size ($n\ensuremath{\lesssim}50$), and measure it on several state-of-the-art transmon devices, finding values as high as 16. The quantum volume is linked to system error rates, and is empirically reduced by uncontrolled interactions within the system. It quantifies the largest random circuit of equal width and depth that the computer successfully implements. Quantum computing systems with high-fidelity operations, high connectivity, large calibrated gate sets, and circuit rewriting toolchains are expected to have higher quantum volumes. The quantum volume is a pragmatic way to measure and compare progress toward improved system-wide gate error rates for near-term quantum computation and error-correction experiments.