{
  "id": "1410.2143",
  "version": "v1",
  "published": "2014-10-08T14:44:29.000Z",
  "updated": "2014-10-08T14:44:29.000Z",
  "title": "Absence of Quantum Time Crystals in Ground States",
  "authors": [
    "Haruki Watanabe",
    "Masaki Oshikawa"
  ],
  "comment": "4 pages + Supplementary Information, 1 figure",
  "categories": [
    "cond-mat.stat-mech",
    "cond-mat.other",
    "hep-th",
    "math-ph",
    "math.MP",
    "quant-ph"
  ],
  "abstract": "In analogy with crystalline solids around us, Wilczek recently proposed the idea of \"time crystals\" as phases that spontaneously break the continuous time translation into a discrete subgroup. The proposal stimulated further studies and vigorous debates whether it can be realized in a physical system. However, a precise definition of the time crystal is needed to resolve the issue. Here we first present a definition of time crystals based on the time-dependent correlation functions of the order parameter. We then prove a no-go theorem that rules out the possibility of time crystals defined as such, in the ground state of a general Hamiltonian which consists of only short-range interactions.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2014-10-08T14:44:29.000Z"
    }
  ],
  "analyses": {
    "subjects": [
      "11.30.-j",
      "05.70.Ln",
      "73.22.Gk"
    ],
    "keywords": [
      "quantum time crystals",
      "ground state",
      "time-dependent correlation functions",
      "no-go theorem",
      "order parameter"
    ],
    "publication": {
      "doi": "10.1103/PhysRevLett.114.251603",
      "journal": "Physical Review Letters",
      "year": 2015,
      "month": "Jun",
      "volume": 114,
      "number": 25,
      "pages": 251603
    },
    "note": {
      "typesetting": "TeX",
      "pages": 4,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1321015,
      "adsabs": "2015PhRvL.114y1603W"
    }
  }
}