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Classical shadows with arbitrary group representations

arXiv Quantum Physics
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⚡ Quantum Brief
Researchers led by Maxwell West introduced a unified framework for classical shadows (CS) protocols, generalizing them to arbitrary group representations. This advances beyond prior case-by-case studies by providing a systematic approach to quantum state prediction. The team identified "centralizing bases," a new class of measurement bases that analytically characterizes and inverts measurement channels, reducing classical post-processing overhead. This optimization improves efficiency in estimating quantum properties. General sample-complexity bounds were derived, quantifying the measurements needed for precise predictions. These bounds apply universally across different group representations, standardizing protocol performance evaluation. The work enables novel CS protocols using previously unexplored groups, including SU(2) spin/tensor representations, symmetric/orthogonal groups, and the exceptional Lie group G₂. This expands the toolkit for quantum state tomography. Published in April 2026, the study unifies existing CS methods while opening avenues for group-theoretic innovations in quantum information. It bridges theory and practical implementation for near-term quantum devices.
Classical shadows with arbitrary group representations

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Quantum Physics arXiv:2604.01429 (quant-ph) [Submitted on 1 Apr 2026] Title:Classical shadows with arbitrary group representations Authors:Maxwell West, Frederic Sauvage, Aniruddha Sen, Roy Forestano, David Wierichs, Nathan Killoran, Dmitry Grinko, M. Cerezo, Martin Larocca View a PDF of the paper titled Classical shadows with arbitrary group representations, by Maxwell West and 8 other authors View PDF HTML (experimental) Abstract:Classical shadows (CS) has recently emerged as an important framework to efficiently predict properties of an unknown quantum state. A common strategy in CS protocols is to parametrize the basis in which one measures the state by a random group action; many examples of this have been proposed and studied on a case-by-case basis. In this work, we present a unified theory that allows us to simultaneously understand CS protocols based on sampling from general group representations, extending previous approaches that worked in simplified (multiplicity-free) settings. We identify a class of measurement bases which we call "centralizing bases" that allows us to analytically characterize and invert the measurement channel, minimizing classical post-processing costs. We complement this analysis by deriving general bounds on the sample-complexity necessary to obtain estimates of a given precision. Beyond its unification of previous CS protocols, our method allows us to readily generate new protocols based on other groups, or different representations of previously considered ones. For example, we characterize novel shadow protocols based on sampling from the spin and tensor representations of $\textsf{SU}(2)$, symmetric and orthogonal groups, and the exceptional Lie group $G_2$. Comments: Subjects: Quantum Physics (quant-ph) Report number: LA-UR-25-27225 Cite as: arXiv:2604.01429 [quant-ph] (or arXiv:2604.01429v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2604.01429 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Maxwell West [view email] [v1] Wed, 1 Apr 2026 22:09:44 UTC (481 KB) Full-text links: Access Paper: View a PDF of the paper titled Classical shadows with arbitrary group representations, by Maxwell West and 8 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2026-04 References & Citations INSPIRE HEP NASA ADSGoogle Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... Data provided by: Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv (What is alphaXiv?) Links to Code Toggle CatalyzeX Code Finder for Papers (What is CatalyzeX?) DagsHub Toggle DagsHub (What is DagsHub?) GotitPub Toggle Gotit.pub (What is GotitPub?) Huggingface Toggle Hugging Face (What is Huggingface?) ScienceCast Toggle ScienceCast (What is ScienceCast?) Demos Demos Replicate Toggle Replicate (What is Replicate?) Spaces Toggle Hugging Face Spaces (What is Spaces?) Spaces Toggle TXYZ.AI (What is TXYZ.AI?) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower (What are Influence Flowers?) Core recommender toggle CORE Recommender (What is CORE?) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs. Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)

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Source: arXiv Quantum Physics