We investigate the zero-temperature quantum phases of a Bose-Bose mixture on a triangular lattice using the bosonic dynamical mean-field theory (BDMFT). We consider the case of total filling where geometric frustration arises for asymmetric hopping. We map out a rich ground-state phase diagram including $xy$ -ferromagnetic, spin-density wave, superfluid, and supersolid phases. In particular, we identify a stripe spin-density wave phase for highly asymmetric hopping. On top of the spin-density wave, we find that the system generically shows weak charge (particle) density wave order.We investigate the zero-temperature quantum phases of a Bose-Bose mixture on a triangular lattice using the bosonic dynamical mean-field theory (BDMFT). We consider the case of total filling where geometric frustration arises for asymmetric hopping. We map out a rich ground-state phase diagram including $xy$-ferromagnetic, spin-density wave, superfluid, and supersolid phases. In particular, we identify a stripe spin-density wave phase for highly asymmetric hopping. On top of the spin-density wave, we find that the system generically shows weak charge (particle) density wave order.

arXiv:1205.1806Physical Review AOct 19, 201224 citations

Superfluid Bose-Fermi mixture from weak coupling to unitarity

Sadhan K. Adhikari, Luca Salasnich

We investigate the zero-temperature properties of a superfluid Bose-Fermi mixture by introducing a set of coupled Galilei-invariant nonlinear Schr\"odinger equations valid from weak coupling to unitarity. The Bose dynamics is described by a Gross-Pitaevskii-type equation including beyond-mean-field corrections possessing the correct weak-coupling and unitarity limits. The dynamics of the two-component Fermi superfluid is described by a density-functional equation including beyond-mean-field terms with correct weak-coupling and unitarity limits. The present set of equations is equivalent to the equations of generalized superfluid hydrodynamics, which take into account also surface effects. The equations describe the mixture properly as the Bose-Bose repulsive (positive) and Fermi-Fermi attractive (negative) scattering lengths are varied from zero to infinity in the presence of a Bose-Fermi interaction. The present model is tested numerically as the Bose-Bose and Fermi-Fermi scattering lengths are varied over wide ranges covering the weak-coupling to unitarity transition.We investigate the zero-temperature properties of a superfluid Bose-Fermi mixture by introducing a set of coupled Galilei-invariant nonlinear Schr\"odinger equations valid from weak coupling to unitarity. The Bose dynamics is described by a Gross-Pitaevskii-type equation including beyond-mean-field corrections possessing the correct weak-coupling and unitarity limits. The dynamics of the two-component Fermi superfluid is described by a density-functional equation including beyond-mean-field terms with correct weak-coupling and unitarity limits. The present set of equations is equivalent to the equations of generalized superfluid hydrodynamics, which take into account also surface effects. The equations describe the mixture properly as the Bose-Bose repulsive (positive) and Fermi-Fermi attractive (negative) scattering lengths are varied from zero to infinity in the presence of a Bose-Fermi interaction. The present model is tested numerically as the Bose-Bose and Fermi-Fermi scattering lengths are varied over wide ranges covering the weak-coupling to unitarity transition.

arXiv:0810.5046Physical Review AOct 30, 2008105 citations

Quasi-particles at finite temperatures

Heide Narnhofer, Manfred Requardt, Walter E Thirring

Communications in Mathematical PhysicsJun 1, 198372 citations

Dissipative effects on the localization of a charged oscillator in a magnetic field

X. L. Li, G. W. Ford, Robert F. O’Connell

We consider the effect of dissipation on a charged, quantum harmonic oscillator coupled to a heat bath, in the presence of an external magnetic field. General conclusions about the equal-time position autocorrelation functions can be reached by using only those properties of the generalized susceptibility tensor imposed by fundamental physical principles. Explicit calculations are made for an Ohmic heat bath at zero temperature, enabling us to show that (unlike the problem without the magnetic field where dissipation always leads to enhanced localization) when the magnetic field is stronger than a certain critical value, weak dissipation actually delocalizes the oscillation of the charged particle.We consider the effect of dissipation on a charged, quantum harmonic oscillator coupled to a heat bath, in the presence of an external magnetic field. General conclusions about the equal-time position autocorrelation functions can be reached by using only those properties of the generalized susceptibility tensor imposed by fundamental physical principles. Explicit calculations are made for an Ohmic heat bath at zero temperature, enabling us to show that (unlike the problem without the magnetic field where dissipation always leads to enhanced localization) when the magnetic field is stronger than a certain critical value, weak dissipation actually delocalizes the oscillation of the charged particle.

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topicsApr 1, 199623 citations

xy

-ferromagnetic, spin-density wave, superfluid, and supersolid phases. In particular, we identify a stripe spin-density wave phase for highly asymmetric hopping. On top of the spin-density wave, we find that the system generically shows weak charge (particle) density wave order.