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    "headline": "Entanglement Closed the Spectrum-Estimation Bound",
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    "dek": "An estimator matched the lower bound while unentangled strategies paid an extra factor in dimension.",
    "summary": "An estimator matched the lower bound while unentangled strategies paid an extra factor in dimension.",
    "body_text": "The paper gives an optimal quantum spectrum-estimation procedure and separates it from unentangled measurements by a factor tied to system dimension. The authors conjecture the unentangled bound is itself optimal; this is a complexity result, not an experimental measurement.",
    "why_it_matters": "An estimator matched the lower bound while unentangled strategies paid an extra factor in dimension.",
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      "The authors conjecture the unentangled bound is itself optimal; this is a complexity result, not an experimental measurement."
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    "tags": [
      "quantum estimation",
      "spectrum learning",
      "measurement complexity"
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  "sources": [
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      "title": "arXiv preprint 2609.30171",
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    "title": "Entanglement Closed the Spectrum-Estimation Bound",
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