Observable Estimation in the Absence of Classical Verification

Authors:Samantha V. Barron, Bradley Mitchell, Vinay Tripathi, Francesco Grieco, Ilan Rosen, Francesca Pietracaprina, Davide Materia, Alireza Seif, Darvin Wanisch, Ramón L. Panadés-Barrueta, Ewout van den Berg, Jay-U Chung, Andrew Eddins, Sam Ferracin, Guillermo García-Pérez, John Goold, Luke C. G. Govia, Holger Haas, Ian Hincks, Jesse C. Hoke, Zoë Holmes, Su-un Lee, Youngseok Kim, Swarnadeep Majumder, Sabrina Maniscalco, Simone Montangero, Daniel Puzzuoli, Tomaž Prosen, James Raftery, Ricardo Rivera Cardoso, Max Rossmannek, Manuel Rudolph, Brendan Saxberg, Liran Shirizly, Karthik Siva, Joshua Skanes-Norman, Ilaria Siloi, Kevin C Smith, Boris Sokolov, Maika Takita, Yanting Teng, Mao Tian Tan, Joseph Tindall, Zoltán Zimborás, Matteo A.C. Rossi, Minh C. Tran, Sergei N. Filippov, Abhinav Kandala

Abstract:The predictive success of quantum mechanics underpins many areas of modern science, even as the exact simulation of large, interacting quantum systems remains beyond the reach of classical computation. This success has been enabled by the remarkable advancement of scalable numerical approximation methods, which often demonstrate practical accuracy despite the absence of formal guarantees. As quantum simulation pushes into regimes where these approximations struggle, a fundamental challenge arises: How can quantum outcomes be trusted when reliable classical benchmarks are unavailable? Here, we establish a framework for the independent validation of quantum estimates in this setting and present evidence that they provide the most credible result among several considered methods, in the absence of an immediately accessible ground-truth solution. We apply our framework to the semi-scrambling dynamics of a physical model that strains several leading classical simulation methods yet remains experimentally accessible, in part through our introduction of the \textit{operator Loschmidt echo}. We systematically design a series of experiments using quantum heuristics that, taken together, test the underlying assumptions and provide strong confidence in the observable estimates obtained from the quantum computer. We then show how this framework can be extended to place accuracy bounds on quantum estimates via careful characterization and manipulation of the device noise, transforming the problem of validating the observable estimation to validating the noise model. These results establish a route towards trusted quantum computation for scientific discovery, independent of classical verification.

arXiv:2607.25998 [quant-ph]

(or arXiv:2607.25998v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2607.25998 arXiv-issued DOI via DataCite (pending registration)