{
  "annotation_id": "9d487d2e-0352-4b56-b526-d2aaa105e51e",
  "date_created": "2026-03-02T18:02:27.663000Z",
  "date_modified": "2026-03-02T18:02:27.663000Z",
  "file_hash": "d730db66c6615c0958b71c08c62f2f51d36bbe7605147dcb89e423d5358ba519",
  "private": false,
  "record": {
    "abstract": "Recently, an explicit protocol ${\\cal E}_0$ for faithfully teleporting\narbitrary two-qubit states using genuine four-qubit entangled states was\npresented by us [Phys. Rev. Lett. {\\bf 96}, 060502 (2006)]. Here, we show that\n${\\cal E}_0$ with an arbitrary four-qubit mixed state resource $\\Xi$ is\nequivalent to a generalized depolarizing bichannel with probabilities given by\nthe maximally entangled components of the resource. These are defined in terms\nof our four-qubit entangled states. We define the generalized singlet fraction\n${\\cal G}[\\Xi]$, and illustrate its physical significance with several\nexamples. We argue that in order to teleport arbitrary two-qubit states with\naverage fidelity better than is classically possible, we have to demand that\n${\\cal G}[\\Xi] \u003e 1/2$. In addition, we conjecture that when ${\\cal G}[\\Xi] \u003c\n1/4$ then no entanglement can be teleported. It is shown that to determine the\nusefulness of $\\Xi$ for ${\\cal E}_0$, it is necessary to analyze ${\\cal\nG}[\\Xi]$.",
    "arxiv_id": "quant-ph/0607108",
    "authors": [
      "Ye Yeo"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevA.74.052305",
    "title": "Teleportation with a Mixed State of Four Qubits and the Generalized   Singlet Fraction",
    "url": "https://arxiv.org/abs/quant-ph/0607108"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "92f9d714-1d7d-4127-aa83-02e6f4827814",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}