{
  "id": "1305.1226",
  "version": "v3",
  "published": "2013-05-06T15:41:28.000Z",
  "updated": "2013-10-21T15:05:21.000Z",
  "title": "Ground state of three qubits coupled to a harmonic oscillator with ultrastrong coupling",
  "authors": [
    "Li-Tuo Shen",
    "Zhen-Biao Yang",
    "Rong-Xin Chen"
  ],
  "comment": "5 pages, 2 figures, Physical Review A 88, 045803 (2013)",
  "journal": "Phys. Rev. A 88, 045803 (2013)",
  "doi": "10.1103/PhysRevA.88.045803",
  "categories": [
    "quant-ph"
  ],
  "abstract": "We study the Rabi model composed of three qubits coupled to a harmonic oscillator without involving the rotating-wave approximation. We show that the ground state of the three-qubit Rabi model can be analytically treated by using the transformation method, and the transformed ground state agrees well with the exactly numerical simulation under a wide range of qubit-oscillator coupling strengths for different detunings. We use the pairwise entanglement to characterize the ground-state entanglement between any two qubits and show that it has an approximately quadratic dependence on the qubit-oscillator coupling strength. Interestingly, we find that there is no qubit-qubit entanglement for the ground state if the qubit-oscillator coupling strength is large enough.",
  "revisions": [
    {
      "version": "v3",
      "updated": "2013-10-21T15:05:21.000Z"
    }
  ],
  "analyses": {
    "subjects": [
      "42.50.Pq",
      "42.50.Ct",
      "03.65.Ud"
    ],
    "keywords": [
      "harmonic oscillator",
      "qubit-oscillator coupling strength",
      "ultrastrong coupling",
      "entanglement"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "APS",
      "journal": "Physical Review A",
      "year": 2013,
      "month": "Oct",
      "volume": 88,
      "number": 4,
      "pages": "045803"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 5,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2013PhRvA..88d5803S"
    }
  }
}