{
  "id": "0807.1034",
  "version": "v2",
  "published": "2008-07-07T15:27:40.000Z",
  "updated": "2009-04-06T09:54:06.000Z",
  "title": "Pairing in ultracold Fermi gases in the lowest Landau level",
  "authors": [
    "G. Moller",
    "Th. Jolicoeur",
    "N. Regnault"
  ],
  "comment": "12 pages, 9 figs (best viewed in color), published version with additional evidence for a non-Abelian spin singlet state at filling nu=2/3",
  "journal": "Physical Review A79, 033609 (2009)",
  "doi": "10.1103/PhysRevA.79.033609",
  "categories": [
    "cond-mat.mes-hall",
    "cond-mat.str-el"
  ],
  "abstract": "We study a rapidly rotating gas of unpolarized spin-1/2 ultracold fermions in the two-dimensional regime when all atoms reside in the lowest Landau level. Due to the presence of the spin degree of freedom both s-wave and p-wave interactions are allowed at ultralow temperatures. We investigate the phase diagram of this system as a function of the filling factor in the lowest Landau level and in terms of the ratio between s- and p-wave interaction strengths. We show that the presence of attractive interactions induces a wide regime of phase separation with formation of maximally compact droplets that are either fully polarized or composed of spin-singlets. In the regime with no phase separation, we give evidence for fractional quantum Hall states. Most notably, we find two distinct singlet states at the filling nu =2/3 for different interactions. One of these states is accounted for by the composite fermion theory while the other one is a paired state for which we identify two competing descriptions with different topological structure. This paired state may be an Abelian liquid of composite spin-singlet Bose molecules with Laughlin correlations. Alternatively, it may be a known non-Abelian paired state, indicated by good overlaps with the corresponding trial wavefunction. By fine tuning of the scattering lengths it is possible to create the non-Abelian critical Haldane-Rezayi state for nu =1/2 and the permanent state of Moore and Read for nu =1. For purely repulsive interactions, we also find evidence for a gapped Halperin state at nu=2/5.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2009-04-06T09:54:06.000Z"
    }
  ],
  "analyses": {
    "subjects": [
      "03.75.Kk",
      "05.30.Jp",
      "73.43.Lp"
    ],
    "keywords": [
      "lowest landau level",
      "ultracold fermi gases",
      "paired state",
      "composite spin-singlet bose molecules",
      "phase separation"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "APS",
      "journal": "Physical Review A",
      "year": 2009,
      "month": "Mar",
      "volume": 79,
      "number": 3,
      "pages": "033609"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 12,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2009PhRvA..79c3609M"
    }
  }
}