{
  "id": "1103.4054",
  "version": "v1",
  "published": "2011-03-21T15:31:37.000Z",
  "updated": "2011-03-21T15:31:37.000Z",
  "title": "Can we always get the entanglement entropy from the Kadanoff-Baym equations? The case of the T-matrix approximation",
  "authors": [
    "M. Puig von Friesen",
    "C. Verdozzi",
    "C. -O. Almbladh"
  ],
  "comment": "6 pages, 6 figures",
  "categories": [
    "cond-mat.mes-hall",
    "cond-mat.quant-gas",
    "cond-mat.str-el"
  ],
  "abstract": "We study the time-dependent transmission of entanglement entropy through an out-of-equilibrium model interacting device in a quantum transport set-up. The dynamics is performed via the Kadanoff-Baym equations within many-body perturbation theory. The double occupancy $< \\hat{n}_{R \\uparrow} \\hat{n}_{R \\downarrow} >$, needed to determine the entanglement entropy, is obtained from the equations of motion of the single-particle Green's function. A remarkable result of our calculations is that $< \\hat{n}_{R \\uparrow} \\hat{n}_{R \\downarrow} >$ can become negative, thus not permitting to evaluate the entanglement entropy. This is a shortcoming of approximate, and yet conserving, many-body self-energies. Among the tested perturbation schemes, the $T$-matrix approximation stands out for two reasons: it compares well to exact results in the low density regime and it always provides a non-negative $< \\hat{n}_{R \\uparrow} \\hat{n}_{R \\downarrow} >$. For the second part of this statement, we give an analytical proof. Finally, the transmission of entanglement across the device is diminished by interactions but can be amplified by a current flowing through the system.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2011-03-21T15:31:37.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "entanglement entropy",
      "kadanoff-baym equations",
      "t-matrix approximation",
      "low density regime",
      "many-body perturbation theory"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1209/0295-5075/95/27005",
      "journal": "EPL (Europhysics Letters)",
      "year": 2011,
      "month": "Jul",
      "volume": 95,
      "number": 2,
      "pages": 27005
    },
    "note": {
      "typesetting": "TeX",
      "pages": 6,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2011EL.....9527005V"
    }
  }
}