Fractional-filling loophole insulator domains for ultracold bosons in optical superlattices
- Dipartimento di Fisica, Politecnico di Torino and INFM, Corso Duca degli Abruzzi 24, I-10129 Torino (Italy)
The zero-temperature phase diagram of a Bose-Einstein condensate confined in realistic one-dimensional l-periodic optical superlattices is investigated. The system of interacting bosons is modeled in terms of a Bose-Hubbard Hamiltonian whose site-dependent local potentials and hopping amplitudes reflect the periodicity of the lattice partition in l-site cells. Relying on the exact mapping between the hardcore limit of the boson Hamiltonian and the model of spinless noninteracting fermions, incompressible insulator domains are shown to exist for rational fillings that are predicted to be compressible in the atomic limit. The corresponding boundaries, qualitatively described in a multiple-site mean-field approach, are shown to exhibit an unusual loophole shape. A more quantitative description of the loophole domain boundaries at half filling for the special case l=2 is supplied in terms of analytic strong-coupling expansions and quantum Monte Carlo simulations.
- OSTI ID:
- 20649884
- Journal Information:
- Physical Review. A, Vol. 70, Issue 6; Other Information: DOI: 10.1103/PhysRevA.70.061603; (c) 2004 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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