We recently studied a doped two-dimensional bosonic Hubbard model with two hard-core species, with different masses, using quantum Monte Carlo simulations [Hettiarachchilage, Phys. Rev. B 88, 161101(R) (2013)]. Upon doping away from half filling, we find several distinct phases, including a phase-separated ferromagnet with Mott behavior for the heavy species and both Mott-insulating and superfluid behaviors for the light species. Introducing polarization, i.e., an imbalance in the population between species, we find a fully phase-separated ferromagnet. This phase exists for a broad range of temperatures and polarizations. By using finite-size scaling of the susceptibility, we find a critical exponent which is consistent with the two-dimensional Ising universality class. Significantly, since the global entropy of this phase is higher than that of the ferromagnetic phase with single species, its experimental observation in cold atoms may be feasible.We recently studied a doped two-dimensional bosonic Hubbard model with two hard-core species, with different masses, using quantum Monte Carlo simulations [Hettiarachchilage, Phys. Rev. B 88, 161101(R) (2013)]. Upon doping away from half filling, we find several distinct phases, including a phase-separated ferromagnet with Mott behavior for the heavy species and both Mott-insulating and superfluid behaviors for the light species. Introducing polarization, i.e., an imbalance in the population between species, we find a fully phase-separated ferromagnet. This phase exists for a broad range of temperatures and polarizations. By using finite-size scaling of the susceptibility, we find a critical exponent which is consistent with the two-dimensional Ising universality class. Significantly, since the global entropy of this phase is higher than that of the ferromagnetic phase with single species, its experimental observation in cold atoms may be feasible.

arXiv:1405.4849Physical Review BNov 4, 20140 citations

Magnetism and phase separation in the ground state of the Hubbard model

R. Zitzler, Thomas Pruschke, R. Bulla

arXiv:cond-mat/0201145The European Physical Journal BJun 1, 200296 citations

Complex phases in the doped two-species bosonic Hubbard model

Kalani Hettiarachchilage, V. G. Rousseau, Ka-Ming Tam +2 more

We study a doped two-dimensional bosonic Hubbard model with two hard-core species using quantum Monte Carlo simulations. With doping we find five distinct phases, including a normal liquid at higher temperature, an antiferromagnetically ordered Mott insulator, a region of coexistent antiferromagnetic and superfluid phases near half filling, and farther away from half filling, a superfluid phase and a phase-separated ferromagnet. In the latter, the heavy species has Mott behavior with integer fillings, while the light species shows Mott and superfluid behaviors. The global entropy of this phase is relatively high which may provide a new avenue to obtain a polarized phase or a Mott insulator in cold-atom experiments.We study a doped two-dimensional bosonic Hubbard model with two hard-core species using quantum Monte Carlo simulations. With doping we find five distinct phases, including a normal liquid at higher temperature, an antiferromagnetically ordered Mott insulator, a region of coexistent antiferromagnetic and superfluid phases near half filling, and farther away from half filling, a superfluid phase and a phase-separated ferromagnet. In the latter, the heavy species has Mott behavior with integer fillings, while the light species shows Mott and superfluid behaviors. The global entropy of this phase is relatively high which may provide a new avenue to obtain a polarized phase or a Mott insulator in cold-atom experiments.

arXiv:1212.4478Physical Review BOct 4, 20135 citations

Correlated Phases in Bose-Hubbard Models with Simulated Magnetic Fields

Nigel R. Cooper

Bulletin of the American Physical SocietyMar 16, 20100 citations

Exotic Ising dynamics in a Bose-Hubbard model

L. F. Oleiro Seabra, Frank Pollmann

We explore the dynamical properties of a one-dimensional Bose-Hubbard model, where two bosonic species interact via Feshbach resonance. We focus on the region in the phase diagram which is described by an effective, low-energy ferromagnetic Ising model in both transverse and longitudinal fields. In this regime, we numerically calculate the dynamical structure factor of the Bose-Hubbard model using the time-evolving block decimation method. In the ferromagnetic phase, we observe both the continuum of excitations and the bound states in the presence of a longitudinal field. Near the Ising critical point, we observe the celebrated ${E}_{8}$ mass spectrum in the excited states. We also point out possible measurements which could be used to detect these excitations in an optical lattice experiment.We explore the dynamical properties of a one-dimensional Bose-Hubbard model, where two bosonic species interact via Feshbach resonance. We focus on the region in the phase diagram which is described by an effective, low-energy ferromagnetic Ising model in both transverse and longitudinal fields. In this regime, we numerically calculate the dynamical structure factor of the Bose-Hubbard model using the time-evolving block decimation method. In the ferromagnetic phase, we observe both the continuum of excitations and the bound states in the presence of a longitudinal field. Near the Ising critical point, we observe the celebrated ${E}_{8}$ mass spectrum in the excited states. We also point out possible measurements which could be used to detect these excitations in an optical lattice experiment.

arXiv:1303.2408Physical Review BSep 4, 20135 citations

{E}_{8}

mass spectrum in the excited states. We also point out possible measurements which could be used to detect these excitations in an optical lattice experiment.