{
  "id": "1311.5472",
  "version": "v1",
  "published": "2013-11-21T16:37:00.000Z",
  "updated": "2013-11-21T16:37:00.000Z",
  "title": "Reversing quantum trajectories with analog feedback",
  "authors": [
    "G. de Lange",
    "D. Ristè",
    "M. J. Tiggelman",
    "C. Eichler",
    "L. Tornberg",
    "G. Johansson",
    "A. Wallraff",
    "R. N. Schouten",
    "L. DiCarlo"
  ],
  "comment": "5 pages, 4 figures, and Supplementary Information (7 figures)",
  "journal": "Phys. Rev. Lett.112, 080501 (2014)",
  "doi": "10.1103/PhysRevLett.112.080501",
  "categories": [
    "cond-mat.mes-hall",
    "quant-ph"
  ],
  "abstract": "We demonstrate the active suppression of transmon qubit dephasing induced by dispersive measurement, using parametric amplification and analog feedback. By real-time processing of the homodyne record, the feedback controller reverts the stochastic quantum phase kick imparted by the measurement on the qubit. The feedback operation matches a model of quantum trajectories with measurement efficiency $\\tilde{\\eta} \\approx 0.5$, consistent with the result obtained by postselection. We overcome the bandwidth limitations of the amplification chain by numerically optimizing the signal processing in the feedback loop and provide a theoretical model explaining the optimization result.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2013-11-21T16:37:00.000Z"
    }
  ],
  "analyses": {
    "subjects": [
      "03.67.Lx",
      "42.50.Dv",
      "42.50.Pq",
      "85.25.-j"
    ],
    "keywords": [
      "reversing quantum trajectories",
      "analog feedback",
      "measurement",
      "stochastic quantum phase kick",
      "feedback controller reverts"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "APS",
      "journal": "Physical Review Letters",
      "year": 2014,
      "month": "Feb",
      "volume": 112,
      "number": 8,
      "pages": "080501"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 5,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2014PhRvL.112h0501D"
    }
  }
}