{
  "id": "1310.3177",
  "version": "v1",
  "published": "2013-10-11T15:54:08.000Z",
  "updated": "2013-10-11T15:54:08.000Z",
  "title": "Reduced back-action for phase sensitivity 10 times beyond the standard quantum limit",
  "authors": [
    "Justin G. Bohnet",
    "Kevin C. Cox",
    "Matthew A. Norcia",
    "Joshua M. Weiner",
    "Zilong Chen",
    "James K. Thompson"
  ],
  "comment": "9 figures, 1 table",
  "doi": "10.1038/nphoton.2014.151",
  "categories": [
    "quant-ph",
    "physics.atom-ph"
  ],
  "abstract": "Collective measurements can project a system into an entangled state with enhanced sensitivity for measuring a quantum phase, but measurement back-action has limited previous efforts to only modest improvements. Here we use a collective measurement to produce and directly observe, with no background subtraction, an entangled, spin-squeezed state with phase resolution improved in variance by a factor of 10.5(1.5), or 10.2(6) dB, compared to the initially unentangled ensemble of N = 4.8 x 10^5 87Rb atoms. The measurement uses a cavity-enhanced probe of an optical cycling transition to mitigate back-action associated with state-changing transitions induced by the probe. This work establishes collective measurements as a powerful technique for generating entanglement for precision measurement, with potential impacts in biological sensing, communication, navigation, and tests of fundamental physics.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2013-10-11T15:54:08.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "standard quantum limit",
      "phase sensitivity",
      "reduced back-action",
      "work establishes collective measurements",
      "measurement back-action"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "journal": "Nature Photonics",
      "year": 2014,
      "month": "Sep",
      "volume": 8,
      "number": 9,
      "pages": 731
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2014NaPho...8..731B"
    }
  }
}