Abstract (WS-D, poster)

PS-D-1. Ozaki, Jun'ichi
  1. Affiliation: Department of Physics, Kyoto University
  2. Country: Japan
  3. Participation: from 11/7 to 12/9
  4. Keywords: cold atom, non-equilibrium phenomena
  5. Title: Cluster-cluster collision of one-dimensional fermions
    Abstract:
    Recently, many experiments with cold atomic gases have been conducted from interest in the non-equilibrium dynamics of correlated quantum systems. Of these experiments, the mixing dynamics of fermion clusters motivates us to research cluster-cluster collision dynamics in one-dimensional Fermi systems. We adopt the one-dimensional Fermi-Hubbard model and apply the time-dependent density matrix renormalization group method. We simulate collisions between two fermion clusters of spin-up and spin-down, and calculate reflectance of the clusters R changing the particle number in each cluster and the interaction strength between two fermions with up and down spins. We also evaluate the quasi-classical (independent collision) reflectance R^{qc} to compare it with R. The quasi-classical picture is quantitatively valid in the limit of weak interaction, but it is not valid when the interaction is strong.
PS-D-2. Tezuka, Masaki
  1. Affiliation: Department of Physics, Kyoto University
  2. Country: Japan
  3. Participation: from 11/7 to 12/9
  4. Keywords: strongly correlated fermions, Mott transitions, nonequilibrium dynamics
  5. Title: Dynamics of an interacting 1d Fermi system in a quasiperiodic potential
    Abstract:
    Detecting superfluidity in quasi-one-dimensional systems of two-component ultracold fermions has been an interesting issue, since in such systems it is possible to tune the shape of the trapping potential shape, the population imbalance and the interaction between atoms. We study superfluid-insulator transition in an optical lattice system due to a quasiperiodic potential modifying the site potential. The strength of the quasiperiodic potential \lambda at the insulating transition point depends on the atom-atom interaction [1]. We report on the real-time dynamics [2] of the two-component fermions after the trapping potential is removed while the optical lattice with the quasiperiodic potential is kept on. We have adopted the time-dependent density-matrix renormalization (td-DMRG) method. The dynamics strongly depends on \lambda. Procedures to detect superfluidity will also be discussed.
    [1] M. Tezuka and A. M. García-García: Phys. Rev. A 82, 043613 (2010).
    [2] A. M. García-García and M. Tezuka: in preparation.
PS-D-3. Ueda, Suguru
  1. Affiliation: Department of Physics, Kyoto University
  2. Country: Japan
  3. Participation: from 11/7 to 12/9
  4. Keywords: heterostructures of strongly correlated electron systems
  5. Title: Effects of magnetic fields in Mott insulator/band insulator heterostructures
    Abstract:
    In strongly correlated hetero-structures, a non-uniform potential together with correlation effects can lead to novel electronic properties which are not realized in ordinary bulk systems. For example, it was reported experimentally and theoretically that the interface between the band insulator (BI) SrTiO3 and the Mott insulator (MI) LaTiO3 shows a metallic behavior. In this study, we consider a strongly correlated interface of BI and MI, like SrTiO3/LaTiO3, with particular emphasis on effects of magnetic fields at the interface. To this end, we investigate the Hubbard model with long-range Coulomb interaction in the Hartree-Fock approximation. We find intriguing magnetic/charge phase transitions at the interface, which are induced by external magnetic fields. We elucidate that these transitions are caused by the strong coupling between charge and spin degrees of freedom near the interface.