3,699 research outputs found
Correlated Phases of Population Imbalanced Fermi-Fermi Mixtures on an Optical Lattice
We study a two species fermion mixture with different populations on a square
lattice modeled by a Hubbard Hamiltonian with on-site inter-species repulsive
interaction. Such a model can be realized in a cold atom system with fermionic
atoms in two different hyperfine states loaded on an optical lattice and with
tunable inter-species interaction strength via external fields. For a
two-dimensional square lattice, when at least one of the fermion species is
close to half-filling, the system is highly affected by lattice effects. With
the majority species near half-filling and varying densities for the minority
species, we find that several correlated phases emerge as the ground state,
including a spin density wave state, a charge density wave state with stripe
structure, and various p-wave BCS pairing states for both species. We study
this system using a functional renormalization group method, determine its
phase diagram at weak coupling, discuss the origin and characteristics of each
phase, and provide estimates for the critical temperatures.Comment: 5 pages, 4 figures, figures update
Tunable current circulation in triangular quantum-dot metastructures
Advances in fabrication and control of quantum dots allow the realization of
metastructures that may exhibit novel electrical transport phenomena. Here, we
investigate the electrical current passing through one such metastructure, a
system composed of quantum dots placed at the vertices of a triangle. The wave
natural of quantum particles leads to internal current circulation within the
metastructure in the absence of any external magnetic field. We uncover the
relation between its steady-state total current and the internal circulation.
By calculating the electronic correlations in quantum transport exactly, we
present phase diagrams showing where different types of current circulation can
be found as a function of the correlation strength and the coupling between the
quantum dots. Finally, we show that the regimes of current circulation can be
further enhanced or reduced depending on the local spatial distribution of the
interactions, suggesting a single-particle scattering mechanism is at play even
in the strongly-correlated regime. We suggest experimental realizations of
actual quantum-dot metastructures where our predictions can be directly tested.Comment: 5 pages, 4 figures, the Supplemental Information is attached at the
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