{
  "id": "1307.5532",
  "version": "v3",
  "published": "2013-07-21T15:32:03.000Z",
  "updated": "2014-11-05T20:15:07.000Z",
  "title": "Quantum entanglement for two electrons in the excited states of helium-like systems",
  "authors": [
    "Yen-Chang Lin",
    "Yew Kam Ho"
  ],
  "comment": "Final version to be published in Canadian Journal of Physics; more references added; more tables added; discussion expanded",
  "categories": [
    "quant-ph",
    "physics.atom-ph"
  ],
  "abstract": "The quantum entanglement for the two electrons in the excited states of the helium-like atom/ions is investigated using the two-electron wave functions constructed by the B-spline basis. As a measure of the spatial (electron-electron orbital) entanglement, the von Neumann entropy and linear entropy of the reduced density matrix are calculated for the 1s2s 1,3S excited states for systems with some selected Z values from Z=2 to Z=100. Results for the helium atom are compared with other available calculations. We have also investigated the entropies for these excited states when the nucleus charge is reduced from Z=2 to Z=1. At such a critical charge, all the singly-excited states of this system become unbound, and the linear entropies and the von Neumann entropies for the excited states are approaching 1/2 and 1, respectively, the limits for the entropies when one electron is bound to the nucleus, and the other being free.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2014-08-09T09:09:22.000Z",
      "comment": "15 pages, 3 figures, recent references added; discussion expanded; appendix A added",
      "journal": null,
      "doi": null
    },
    {
      "version": "v3",
      "updated": "2014-11-05T20:15:07.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "quantum entanglement",
      "helium-like systems",
      "von neumann entropy",
      "linear entropy",
      "two-electron wave functions"
    ],
    "publication": {
      "doi": "10.1139/cjp-2014-0437",
      "journal": "Canadian Journal of Physics",
      "year": 2015,
      "month": "Jun",
      "volume": 93,
      "number": 6,
      "pages": 646
    },
    "note": {
      "typesetting": "TeX",
      "pages": 15,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2015CaJPh..93..646L"
    }
  }
}