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Main Authors: Bentsen, Gregory, Fefferman, Bill, Ghosh, Soumik, Gullans, Michael J., Liu, Yinchen
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.22909
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author Bentsen, Gregory
Fefferman, Bill
Ghosh, Soumik
Gullans, Michael J.
Liu, Yinchen
author_facet Bentsen, Gregory
Fefferman, Bill
Ghosh, Soumik
Gullans, Michael J.
Liu, Yinchen
contents Random circuit sampling (RCS) remains one of the most competitive frameworks for demonstrating quantum advantage in near-term noisy intermediate-scale quantum (NISQ) hardware. Unfortunately, absent error-correction, existing benchmarks to characterize these experiments, like linear cross-entropy, have been classically spoofed due to noise. Because of this, there are interesting regimes, like shallow-depth random quantum circuits, where sampling is plausibly classically intractable, but no existing benchmark can distinguish between a noisy quantum computer and an adversarial classical spoofer. In this paper, we demonstrate that the nonlinear cross-entropy provides a sample-efficient benchmark for shallow-depth all-to-all random quantum circuits whose score cleanly separates noisy quantum computers from state-of-the-art classical spoofers, even in the presence of depolarizing noise. Further, we develop a binary classifier based on the notion of heavy output generation that features logarithmic sample complexity at short depth. Our evidence comes from exact analytic expressions for all-to-all Brownian circuit ensembles derived using replica tricks, and numerical simulations that corroborate these results for discrete Haar-random unitary circuits.
format Preprint
id arxiv_https___arxiv_org_abs_2605_22909
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Sample-efficient benchmarking of shallow all-to-all random quantum circuits
Bentsen, Gregory
Fefferman, Bill
Ghosh, Soumik
Gullans, Michael J.
Liu, Yinchen
Quantum Physics
Random circuit sampling (RCS) remains one of the most competitive frameworks for demonstrating quantum advantage in near-term noisy intermediate-scale quantum (NISQ) hardware. Unfortunately, absent error-correction, existing benchmarks to characterize these experiments, like linear cross-entropy, have been classically spoofed due to noise. Because of this, there are interesting regimes, like shallow-depth random quantum circuits, where sampling is plausibly classically intractable, but no existing benchmark can distinguish between a noisy quantum computer and an adversarial classical spoofer. In this paper, we demonstrate that the nonlinear cross-entropy provides a sample-efficient benchmark for shallow-depth all-to-all random quantum circuits whose score cleanly separates noisy quantum computers from state-of-the-art classical spoofers, even in the presence of depolarizing noise. Further, we develop a binary classifier based on the notion of heavy output generation that features logarithmic sample complexity at short depth. Our evidence comes from exact analytic expressions for all-to-all Brownian circuit ensembles derived using replica tricks, and numerical simulations that corroborate these results for discrete Haar-random unitary circuits.
title Sample-efficient benchmarking of shallow all-to-all random quantum circuits
topic Quantum Physics
url https://arxiv.org/abs/2605.22909