{
  "id": "quant-ph/0511187",
  "version": "v1",
  "published": "2005-11-18T18:29:52.000Z",
  "updated": "2005-11-18T18:29:52.000Z",
  "title": "Direct measurement of non-linear properties of bipartite quantum states",
  "authors": [
    "Fabio Antonio Bovino",
    "Giuseppe Castagnoli",
    "Artur Ekert",
    "Pawel Horodecki",
    "Carolina Moura Alves",
    "Alexander Vladimir Sergienko"
  ],
  "comment": "To appear on PRL with minor changes",
  "doi": "10.1103/PhysRevLett.95.240407",
  "categories": [
    "quant-ph"
  ],
  "abstract": "Non-linear properties of quantum states, such as entropy or entanglement, quantify important physical resources and are frequently used in quantum information science. They are usually calculated from a full description of a quantum state, even though they depend only on a small number parameters that specify the state. Here we extract a non-local and a non-linear quantity, namely the Renyi entropy, from local measurements on two pairs of polarization entangled photons. We also introduce a \"phase marking\" technique which allows to select uncorrupted outcomes even with non-deterministic sources of entangled photons. We use our experimental data to demonstrate the violation of entropic inequalities. They are examples of a non-linear entanglement witnesses and their power exceeds all linear tests for quantum entanglement based on all possible Bell-CHSH inequalities.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2005-11-18T18:29:52.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "bipartite quantum states",
      "non-linear properties",
      "direct measurement",
      "quantum information science",
      "non-linear entanglement witnesses"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "APS",
      "journal": "Phys. Rev. Lett."
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}