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Entanglement in quantum spin chains is strictly finite at any temperature

arXiv Quantum Physics
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⚡ Quantum Brief
MIT researchers proved that entanglement in quantum spin chains remains strictly finite at any finite temperature, even in the thermodynamic limit. This resolves a key challenge in quantum statistical physics by demonstrating bounded entanglement in thermal equilibrium. The team decomposed Gibbs states of spin chains into matrix product states with bond dimensions independent of system size. This breakthrough provides an exact, size-scalable representation of thermal states using tensor network methods. Their work shows the Schmidt number—a rigorous measure of bipartite entanglement—stays finite for thermal states. This contradicts prior assumptions about unbounded entanglement growth in many-body systems at equilibrium. An efficient classical algorithm accompanies the decomposition, enabling practical sampling of these matrix product states. This bridges theory and computation for studying thermal quantum systems. The findings unify quantum information theory with statistical mechanics, offering new tools to analyze entanglement in realistic, finite-temperature quantum materials and devices.
Entanglement in quantum spin chains is strictly finite at any temperature

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Quantum Physics arXiv:2602.13386 (quant-ph) [Submitted on 13 Feb 2026] Title:Entanglement in quantum spin chains is strictly finite at any temperature Authors:Ainesh Bakshi, Soonwon Choi, Saúl Pilatowsky-Cameo View a PDF of the paper titled Entanglement in quantum spin chains is strictly finite at any temperature, by Ainesh Bakshi and 2 other authors View PDF HTML (experimental) Abstract:Entanglement is the hallmark of quantum physics, yet its characterization in interacting many-body systems at thermal equilibrium remains one of the most important challenges in quantum statistical physics. We prove that the Gibbs state of any quantum spin chain can be exactly decomposed into a mixture of matrix product states with a bond dimension that is independent of the system size, at any finite temperature. As a consequence, the Schmidt number, arguably the most stringent measure of bipartite entanglement, is strictly finite for thermal states, even in the thermodynamic limit. Our decomposition is explicit and is accompanied by an efficient classical algorithm to sample the resulting matrix product states. Comments: Subjects: Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech); Mathematical Physics (math-ph) Report number: MIT-CTP/6005 Cite as: arXiv:2602.13386 [quant-ph] (or arXiv:2602.13386v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2602.13386 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Saúl Pilatowsky-Cameo [view email] [v1] Fri, 13 Feb 2026 19:00:00 UTC (56 KB) Full-text links: Access Paper: View a PDF of the paper titled Entanglement in quantum spin chains is strictly finite at any temperature, by Ainesh Bakshi and 2 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2026-02 Change to browse by: cond-mat cond-mat.stat-mech math math-ph math.MP 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