Fractional-filling Mott domains in two-dimensional optical superlattices

Year: 2005

Authors: Buonsante P., Penna V., Vezzani A.

Autors Affiliation: Dipartimento di Fisica, Politecnico di Torino and I.N.F.M, Corso Duca degli Abruzzi 24, I-10129 Torino, Italy; Dipartimento di Fisica, Università degli Studi di Parma and I.N.F.M., Parco Area delle Scienze 7/a, I-43100 Parma, Italy

Abstract: Ultracold bosons in optical superlattices are expected to exhibit fractional-filling insulating phases for sufficiently large repulsive interactions. On strictly one-dimensional systems, the exact mapping between hard-core bosons and free spinless fermions shows that any periodic modulation in the lattice parameters causes the presence of fractional-filling insulator domains. Here, we focus on two recently proposed realistic two-dimensional structures where such mapping does not hold, i.e., the two-leg ladder and the trimerized kagome lattice. Based on a cell strong-coupling perturbation technique, we provide quantitatively satisfactory phase diagrams for these structures, and give estimates for the occurrence of the fractional-filling insulator domains in terms of the intercell to intracell hopping amplitude ratio.

Journal/Review: PHYSICAL REVIEW A

Volume: 72 (3)      Pages from: 031602-1  to: 031602-4

More Information: Rapid Communication
KeyWords: ultracold atoms; bosons; optical lattice; superlattice; quantum phase transitions
DOI: 10.1103/PhysRevA.72.031602

ImpactFactor: 2.997
Citations: 26
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