{
  "annotation_id": "323e62d4-fbcf-4e81-a905-a3a62e662a96",
  "date_created": "2026-03-02T18:01:56.612000Z",
  "date_modified": "2026-03-02T18:01:56.612000Z",
  "file_hash": "c59fb795c9c1beb6385e36b4602c9e98ea0a07d683d0a5ee986cc1a3cbeebac7",
  "private": false,
  "record": {
    "abstract": "We show that for an m-partite quantum system, there is a ball of radius\n2^{-(m/2-1)} in Frobenius norm, centered at the identity matrix, of separable\n(unentangled) positive semidefinite matrices. This can be used to derive an\nepsilon below which mixtures of epsilon of any density matrix with 1 - epsilon\nof the maximally mixed state will be separable. The epsilon thus obtained is\nexponentially better (in the number of systems) than existing results. This\ngives a number of qubits below which NMR with standard pseudopure-state\npreparation techniques can access only unentangled states; with parameters\nrealistic for current experiments, this is 23 qubits (compared to 13 qubits via\nearlier results). A ball of radius 1 is obtained for multipartite states\nseparable over the reals.",
    "arxiv_id": "quant-ph/0302102",
    "authors": [
      "Leonid Gurvits",
      "Howard Barnum"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevA.68.042312",
    "journal_ref": "Phys. Rev. A 68, 042312 (2003)",
    "title": "Separable balls around the maximally mixed multipartite quantum states",
    "url": "https://arxiv.org/abs/quant-ph/0302102"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "e590c276-0720-4558-a8a9-53e0d5afa85c",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}