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Decohered color code and emerging mixed toric code by anyon proliferation: Topological entanglement negativity perspective

arXiv Quantum Physics
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Japanese researchers demonstrated that decoherence in quantum color codes generates a novel mixed-state topological order, distinct from pure-state systems. Their study reveals how XX-type noise on honeycomb lattices preserves half the original code’s topological properties. The emergent phase resembles a single toric code, confirmed via topological entanglement negativity (TEN) measurements. Pure color codes yield TEN=2ln2, while maximally decohered states drop to TEN=ln2, signaling toric code emergence. Tuning decoherence strength produces a smooth TEN crossover with a system-size-independent variance peak. This suggests a universal transition mechanism in mixed-state topological phases. Negativity scaling only appears in partitions aligned with the emergent toric code’s triangular lattice. The finding highlights negativity’s role as a probe for mixed-state topological order. The work combines stabilizer formalism and gauging procedures to simulate mixed-state dynamics efficiently, offering new tools for studying decoherence-induced topological phases.
Decohered color code and emerging mixed toric code by anyon proliferation: Topological entanglement negativity perspective

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Quantum Physics arXiv:2604.22521 (quant-ph) [Submitted on 24 Apr 2026] Title:Decohered color code and emerging mixed toric code by anyon proliferation: Topological entanglement negativity perspective Authors:Keisuke Kataoka, Yoshihito Kuno, Takahiro Orito, Ikuo Ichinose View a PDF of the paper titled Decohered color code and emerging mixed toric code by anyon proliferation: Topological entanglement negativity perspective, by Keisuke Kataoka and 3 other authors View PDF HTML (experimental) Abstract:We study how the color code under decoherence gives rise to an intrinsic mixed-state topological order (imTO), which has no counterpart in pure ground states of local gapped Hamiltonians. For decoherence induced by XX-type operators on red links of the honeycomb lattice, we show that the resulting mixed state inherits half of the topological properties of the color code, including anyon content, logical operators, and topological entanglement structure. Using a gauging procedure for mixed stabilizer states, we identify the emergent phase as closely related to a single toric code. We characterize this phase by topological entanglement negativity (TEN) and perform efficient stabilizer-formalism simulations. While the pure color code has ${\rm TEN} = 2 \ln 2$, the maximally decohered state has ${\rm TEN} = \ln 2$, indicating emergence of a single toric code. By tuning the decoherence strength, we find a smooth crossover in TEN accompanied by a pronounced, nearly system-size-independent peak in its variance. We further show that the negativity exhibits characteristic scaling only for subsystem partitions commensurate with the triangular lattice of the emergent toric code. Our results demonstrate that negativity-based quantities provide powerful probes of mixed-state topological order generated by decoherence. Comments: Subjects: Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech); Strongly Correlated Electrons (cond-mat.str-el) Cite as: arXiv:2604.22521 [quant-ph] (or arXiv:2604.22521v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2604.22521 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Yoshihito Kuno [view email] [v1] Fri, 24 Apr 2026 13:03:33 UTC (2,028 KB) Full-text links: Access Paper: View a PDF of the paper titled Decohered color code and emerging mixed toric code by anyon proliferation: Topological entanglement negativity perspective, by Keisuke Kataoka and 3 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2026-04 Change to browse by: cond-mat cond-mat.stat-mech cond-mat.str-el 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