{
  "id": "quant-ph/0202136",
  "version": "v1",
  "published": "2002-02-25T04:41:51.000Z",
  "updated": "2002-02-25T04:41:51.000Z",
  "title": "Adaptive Phase Measurements",
  "authors": [
    "Dominic Berry"
  ],
  "comment": "PhD thesis, 228 pages, 103 figures",
  "categories": [
    "quant-ph"
  ],
  "abstract": "In this thesis I consider the general problem of how to make the best possible phase measurements using feedback. Both the optimum input state and optimum feedback are considered for both single-mode dyne measurements and two-mode interferometric measurements. I derive the optimum input states under general dyne measurements when the mean photon number is fixed, both for general states and squeezed states. I propose a new feedback scheme that introduces far less phase uncertainty than mark II feedback, and is very close to the theoretical limit. I also derive results for the phase variance when there is a time delay in the feedback loop, showing that there is a lower limit to the introduced phase variance, and this is approached quite accurately under some conditions. I derive the optimum input states for interferometry, showing that the phase uncertainty scales as 1/N for all the common measures of uncertainty. This is contrasted with the |j0>_z state, which does not scale as 1/N for all measures of phase uncertainty. I introduce an adaptive feedback scheme that is very close to optimum, and can give scaling very close to 1/N for the uncertainty. Lastly I consider the case of continuous measurements, for both the dyne and interferometric cases.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2002-02-25T04:41:51.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "adaptive phase measurements",
      "optimum input state",
      "feedback scheme",
      "phase variance",
      "two-mode interferometric measurements"
    ],
    "tags": [
      "dissertation"
    ],
    "publication": {
      "journal": "Ph.D. Thesis",
      "year": 2002,
      "month": "Feb"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 228,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2002PhDT.......191B"
    }
  }
}