We theoretically address magnetic ordering at zero and finite temperature in both homogeneous and trapped Bose-Bose mixtures in optical lattices. By using bosonic dynamical mean-field theory, we obtain the phase diagram of the homogeneous two-component Bose-Hubbard model in a three-dimensional cubic lattice, which features competing magnetic order of $XY$ ferromagnetic and antiferromagnetic type in addition to the Mott and superfluid states. We show that these magnetic phases persist also in the presence of a harmonic trap.We theoretically address magnetic ordering at zero and finite temperature in both homogeneous and trapped Bose-Bose mixtures in optical lattices. By using bosonic dynamical mean-field theory, we obtain the phase diagram of the homogeneous two-component Bose-Hubbard model in a three-dimensional cubic lattice, which features competing magnetic order of $XY$ ferromagnetic and antiferromagnetic type in addition to the Mott and superfluid states. We show that these magnetic phases persist also in the presence of a harmonic trap.

arXiv:1105.4886Physical Review BOct 5, 201136 citations

COLLECTIVE MODES OF TRAPPED INTERACTING BOSONS

G. GNANAPRAGASAM, Mrinmay Das

Dec 1, 20080 citations

Ising antiferromagnet with ultracold bosonic mixtures confined in a harmonic trap

Marco Guglielmino, Vittorio Penna, Barbara Capogrosso-Sansone

We present accurate results based on quantum Monte Carlo simulations of two-component bosonic systems on a square lattice and in the presence of an external harmonic confinement. Starting from hopping parameters and interaction strengths which stabilize the Ising antiferromagnetic phase in the homogeneous case and at half-integer filling factor, we study how the presence of the harmonic confinement challenges the realization of such a phase. We consider realistic trapping frequencies and number of particles, and we establish under which conditions, i.e., total number of particles and population imbalance, the antiferromagnetic phase can be observed in the trap.We present accurate results based on quantum Monte Carlo simulations of two-component bosonic systems on a square lattice and in the presence of an external harmonic confinement. Starting from hopping parameters and interaction strengths which stabilize the Ising antiferromagnetic phase in the homogeneous case and at half-integer filling factor, we study how the presence of the harmonic confinement challenges the realization of such a phase. We consider realistic trapping frequencies and number of particles, and we establish under which conditions, i.e., total number of particles and population imbalance, the antiferromagnetic phase can be observed in the trap.

arXiv:1105.5293Physical Review ASep 20, 201115 citations

Phase Separation in Ultracold Boson–Fermion Mixtures under Confinement

Z. Akdeniz, M. P. Tosi

Abstract A short review is given of recent progress in understanding the demixing transition in a mesoscopic gaseous cloud of bosonic and fermionic alkali atoms under the effect of their mutual repulsions at zero temperature. The mixture is confined inside a magnetic trap exerting external harmonic potentials on the atoms and the bosonic component is taken in a Bose-Einstein condensed state while the fermions are in a spin-polarized state. Main emphasis is placed on the role of the confinement: in a mesoscopic system (i) the phase transition becomes smooth as a function of the driving parameter, which is the boson-fermion s-wave scattering length; and (ii) various configurations of the phase-separated gaseous cloud are allowed, including some very exotic ones in an anisotropic trap. The transition inside a spherical trap leads to an egg-type structure, with the bosonic condensate being surrounded by a shell of fermions, and is best identified from a sharp upturn of the frequency of low-lying monopolar and dipolar oscillations of fermionic character. This dynamical signature of the transition appears when the overlap between the two components has already started to decrease, but is still quite appreciable. A system of specific experimental interest is the mixture of 6Li and 7Li isotopes, whose parameters could be driven towards the phase transition.Abstract A short review is given of recent progress in understanding the demixing transition in a mesoscopic gaseous cloud of bosonic and fermionic alkali atoms under the effect of their mutual repulsions at zero temperature. The mixture is confined inside a magnetic trap exerting external harmonic potentials on the atoms and the bosonic component is taken in a Bose-Einstein condensed state while the fermions are in a spin-polarized state. Main emphasis is placed on the role of the confinement: in a mesoscopic system (i) the phase transition becomes smooth as a function of the driving parameter, which is the boson-fermion s-wave scattering length; and (ii) various configurations of the phase-separated gaseous cloud are allowed, including some very exotic ones in an anisotropic trap. The transition inside a spherical trap leads to an egg-type structure, with the bosonic condensate being surrounded by a shell of fermions, and is best identified from a sharp upturn of the frequency of low-lying monopolar and dipolar oscillations of fermionic character. This dynamical signature of the transition appears when the overlap between the two components has already started to decrease, but is still quite appreciable. A system of specific experimental interest is the mixture of 6Li and 7Li isotopes, whose parameters could be driven towards the phase transition.

Zeitschrift für Physikalische ChemieAug 1, 20031 citation

Interaction driven quantum phases in spin-orbit-coupled spin-1 bosons

J. H. Pixley, Stefan S. Natu, William S. Cole +2 more

Bulletin of the American Physical SocietyMay 25, 20160 citations

XY

ferromagnetic and antiferromagnetic type in addition to the Mott and superfluid states. We show that these magnetic phases persist also in the presence of a harmonic trap.