51 research outputs found
Multiband-Driven Superfluid-Insulator Transition of Fermionic Atoms in Optical Lattices: A Dynamical Mean-Field-Theory Study
The superfluid-insulator transitions of the fermionic atoms in optical
lattices are investigated by the two-site dynamical mean-field theory. It is
shown that the Mott transition occurs as a result of the multiband effects. The
quasiparticle weight in the superfluid state decreases significantly, as the
system approaches the Mott transition point. By changing the interaction and
the orbital splitting, we obtain the phase diagram at half filling. The
numerical results are discussed in comparison with the effective boson model.Comment: 4 pages, 3 figures, Phys. Rev. A 77, 043624 (2008
Three-Component Fermionic Atoms with Repulsive Interaction in Optical Lattices
We investigate three-component (colors) repulsive fermionic atoms in optical
lattices using the dynamical mean field theory. Depending on the anisotropy of
the repulsive interactions, either a color density-wave state or a color
selective staggered state appears at half filling. In the former state, pairs
of atoms with two of the three colors and atoms with the third color occupy
different sites alternately. In the latter state, atoms with two of the three
colors occupy different sites alternately and atoms with the third color are
itinerant throughout the system. When the interactions are isotropic, both
states are degenerate. We discuss the results using an effective model.Comment: 5 pages, 5 figure
Superfluid state of repulsively interacting three-component fermionic atoms in optical lattices
We investigate the superfluid state of repulsively interacting
three-component (color) fermionic atoms in optical lattices. When the
anisotropy of the three repulsive interactions is strong, atoms of two of the
three colors form Cooper pairs and atoms of the third color remain a Fermi
liquid. An effective attractive interaction is induced by density fluctuations
of the third-color atoms. This superfluid state is stable against changes in
filling close to half filling. We determine the phase diagrams in terms of
temperature, filling, and the anisotropy of the repulsive interactions.Comment: 5 pages, 6 figure
Mott Transitions of Three-Component Fermionic Atoms with Repulsive Interaction in Optical Lattices
We investigate the Mott transitions of three-component (colors) repulsive
fermionic atoms in optical lattices using the dynamical mean field theory. We
find that for SU(3) symmetry breaking interactions the Mott transition occurs
at incommensurate half filling. As a result, a characteristic Mott insulating
state appears, where paired atoms with two different colors and atoms with the
third color are localized at different sites. We also find another Mott state
where atoms with two different colors are localized at different sites and
atoms with the third color remain itinerant. We demonstrate that these exotic
Mott phases can be detected by experimental double occupancy observations.Comment: 5 pages, 4 figure
Density-Wave and Antiferromagnetic States of Fermionic Atoms in Optical Lattices
We study the two-band effects on ultracold fermionic atoms in optical
lattices by means of dynamical mean-field theory. We find that at half-filling
the atomic-density-wave (ADW) state emerges owing to the two-band effects in
the attractive interaction region, while the antiferromagnetic state appears in
the repulsive interaction region. As the orbital splitting is increased, the
quantum phase transitions from the ADW state to the superfluid state and from
the antiferromagnetic state to the metallic state occur in respective regions.
Systematically changing the orbital splitting and the interaction, we obtain
the phase diagram at half-filling. The results are discussed using the
effective boson model derived for the strong attractive interaction.Comment: 7 pages, 7 figure
Supersolid state in fermionic optical lattice systems
We study ultracold fermionic atoms trapped in an optical lattice with
harmonic confinement by combining the real-space dynamical mean-field theory
with a two-site impurity solver. By calculating the local particle density and
the pair potential in the systems with different clusters, we discuss the
stability of a supersolid state, where an s-wave superfluid coexists with a
density-wave state of checkerboard pattern. It is clarified that a confining
potential plays an essential role in stabilizing the supersolid state. The
phase diagrams are obtained for several effective particle densities.Comment: 7 pages, 5 figures, Phys. Rev. A in pres
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