Ultracold fermions in a one-dimensional bipartite optical lattice: Metal-insulator transitions driven by shaking

M. Di Liberto, D. Malpetti, G. I. Japaridze, and C. Morais Smith
Phys. Rev. A 90, 023634 – Published 29 August 2014

Abstract

We theoretically investigate the behavior of a system of fermionic atoms loaded in a bipartite one-dimensional optical lattice that is under the action of an external time-periodic driving force. By using Floquet theory, an effective model is derived. The bare hopping coefficients are renormalized by zeroth-order Bessel functions of the first kind with different arguments for the nearest-neighbor and next-nearest-neighbor hopping. The insulating behavior characterizing the system at half filling in the absence of driving is dynamically suppressed, and for particular values of the driving parameter the system becomes either a standard metal or an unconventional metal with four Fermi points. The existence of the four-Fermi-point metal relies on the fact that, as a consequence of the shaking procedure, the next-nearest-neighbor hopping coefficients become significant compared to the nearest-neighbor ones. We use the bosonization technique to investigate the effect of on-site Hubbard interactions on the four-Fermi-point metal-insulator phase transition. Attractive interactions are expected to enlarge the regime of parameters where the unconventional metallic phase arises, whereas repulsive interactions reduce it. This metallic phase is known to be a Luther-Emery liquid (spin-gapped metal) for both repulsive and attractive interactions, contrary to the usual Hubbard model, which exhibits a Mott-insulator phase for repulsive interactions. Ultracold fermions in driven one-dimensional bipartite optical lattices provide an interesting platform for the realization of this long-studied four-Fermi-point unconventional metal.

    • Received 20 May 2014

    DOI:https://doi.org/10.1103/PhysRevA.90.023634

    ©2014 American Physical Society

    Authors & Affiliations

    M. Di Liberto1, D. Malpetti1,2, G. I. Japaridze3,4, and C. Morais Smith1

    • 1Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584CE Utrecht, The Netherlands
    • 2Department of Physics, University of Pavia-CNISM, Via Bassi 6, I-27100 Pavia, Italy
    • 3Andronikashvili Institute of Physics, Tamarashvili 6, 0177 Tbilisi, Georgia
    • 4Ilia State University, Faculty of Engineering, Cholokasvili Avenue 3-5, 0162 Tbilisi, Georgia

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    Issue

    Vol. 90, Iss. 2 — August 2014

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