{
  "id": "quant-ph/0703261",
  "version": "v1",
  "published": "2007-03-28T15:08:57.000Z",
  "updated": "2007-03-28T15:08:57.000Z",
  "title": "Quantum thermodynamic Carnot and Otto-like cycles for a two-level system",
  "authors": [
    "Gian Paolo Beretta"
  ],
  "comment": "RevTex4, 4 pages, 1 figure",
  "journal": "EPL, 99, 20005 (2012)",
  "doi": "10.1209/0295-5075/99/20005",
  "categories": [
    "quant-ph"
  ],
  "abstract": "From the thermodynamic equilibrium properties of a two-level system with variable energy-level gap $\\Delta$, and a careful distinction between the Gibbs relation $dE = T dS + (E/\\Delta) d\\Delta$ and the energy balance equation $dE = \\delta Q^\\leftarrow - \\delta W^\\to$, we infer some important aspects of the second law of thermodynamics and, contrary to a recent suggestion based on the analysis of an Otto-like thermodynamic cycle between two values of $\\Delta$ of a spin-1/2 system, we show that a quantum thermodynamic Carnot cycle, with the celebrated optimal efficiency $1 - (T_{low}/T_{high})$, is possible in principle with no need of an infinite number of infinitesimal processes, provided we cycle smoothly over at least three (in general four) values of $\\Delta$, and we change $\\Delta$ not only along the isoentropics, but also along the isotherms, e.g., by use of the recently suggested maser-laser tandem technique. We derive general bounds to the net-work to high-temperature-heat ratio for a Carnot cycle and for the 'inscribed' Otto-like cycle, and represent these cycles on useful thermodynamic diagrams.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2007-03-28T15:08:57.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "two-level system",
      "otto-like cycle",
      "quantum thermodynamic carnot cycle",
      "maser-laser tandem technique",
      "energy balance equation"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "journal": "EPL (Europhysics Letters)",
      "year": 2012,
      "month": "Jul",
      "volume": 99,
      "number": 2,
      "pages": 20005
    },
    "note": {
      "typesetting": "RevTeX",
      "pages": 4,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2012EL.....9920005B"
    }
  }
}