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Intractability of Witnessing Entangled Measurements Device Independently

arXiv Quantum Physics
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⚡ Quantum Brief
Peter Bierhorst’s new study challenges the feasibility of device-independent certification for entangled measurements, a cornerstone of quantum information theory. Published in February 2026, the work undermines prior protocols claiming to verify entangled measurements without trusting the devices involved. The paper introduces countermodels where supposedly entangled measurements can be replicated using non-entangled processes. This reveals a fundamental loophole: entanglement can always be shifted from measurements to the measured states in black-box scenarios. Bierhorst demonstrates that no device-independent protocol can definitively prove a measurement is entangled. The findings suggest entangled measurements may not be essential for replicating observed quantum behaviors in these setups. This research reshapes understanding of quantum certification, implying current methods cannot distinguish true entangled measurements from clever classical mimics. It questions the operational meaning of entanglement in measurements. The work has broad implications for quantum cryptography, computing, and foundational physics, forcing a reevaluation of how entanglement is detected and verified in untrusted-device scenarios.
Intractability of Witnessing Entangled Measurements Device Independently

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Quantum Physics arXiv:2602.15199 (quant-ph) [Submitted on 16 Feb 2026] Title:Intractability of Witnessing Entangled Measurements Device Independently Authors:Peter Bierhorst View a PDF of the paper titled Intractability of Witnessing Entangled Measurements Device Independently, by Peter Bierhorst View PDF Abstract:Protocols have been previously proposed to certify the presence of an entangled measurement in a fully device-independent manner. Here, I provide models for these protocols in which the claimed measurement is not entangled, and demonstrate it is always possible to displace entanglement from measurements to measured states for a general class of device-independent scenarios. This indicates that no black-box measurement scenario requires entangled measurements to replicate its behavior, which is relevant to our fundamental understanding of this phenomenon and how to witness it. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2602.15199 [quant-ph] (or arXiv:2602.15199v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2602.15199 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Peter Bierhorst [view email] [v1] Mon, 16 Feb 2026 21:29:36 UTC (283 KB) Full-text links: Access Paper: View a PDF of the paper titled Intractability of Witnessing Entangled Measurements Device Independently, by Peter BierhorstView PDFTeX Source view license Current browse context: quant-ph new | recent | 2026-02 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?) Links to Code Toggle Papers with Code (What is Papers with Code?) 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