A time-dependent optical lattice with staggered particle current in the tight-binding regime was considered that can be described by a time-independent effective lattice model with an artificial staggered magnetic field. The low-energy description of a single-component fermion in this lattice at half-filling is provided by two copies of ideal two-dimensional massless Dirac fermions. The Dirac cones are generally anisotropic and can be tuned by the external staggered flux $\ensuremath{\phi}$. For bosons, the staggered flux modifies the single-particle spectrum such that in the weak coupling limit, depending on the flux $\ensuremath{\phi}$, distinct superfluid phases are realized. Their properties are discussed, the nature of the phase transitions between them is established, and Bogoliubov theory is used to determine their excitation spectra. Then the generalized superfluid--Mott-insulator transition is studied in the presence of the staggered flux and the complete phase diagram is established. Finally, the momentum distribution of the distinct superfluid phases is obtained, which provides a clear experimental signature of each phase in ballistic expansion experiments.A time-dependent optical lattice with staggered particle current in the tight-binding regime was considered that can be described by a time-independent effective lattice model with an artificial staggered magnetic field. The low-energy description of a single-component fermion in this lattice at half-filling is provided by two copies of ideal two-dimensional massless Dirac fermions. The Dirac cones are generally anisotropic and can be tuned by the external staggered flux $\ensuremath{\phi}$. For bosons, the staggered flux modifies the single-particle spectrum such that in the weak coupling limit, depending on the flux $\ensuremath{\phi}$, distinct superfluid phases are realized. Their properties are discussed, the nature of the phase transitions between them is established, and Bogoliubov theory is used to determine their excitation spectra. Then the generalized superfluid--Mott-insulator transition is studied in the presence of the staggered flux and the complete phase diagram is established. Finally, the momentum distribution of the distinct superfluid phases is obtained, which provides a clear experimental signature of each phase in ballistic expansion experiments.

arXiv:0910.2610Physical Review AFeb 4, 201061 citations

Spin model in the effective staggered magnetic field in optical lattices

Huirong Zhang, Qiuyi Guo, Zhaoyuan Ma +1 more

Ultracold atoms with two hyperfine internal states in optical lattices are proposed to demonstrate a two-dimensional spin- $1/2$ model under a transverse effective staggered magnetic field. The transverse magnetic field is produced by a Raman process and can be modulated by the intensities of the additional light fields. This optical lattice protocol can investigate magnetic quantum phenomena induced by the effective staggered magnetic field in a wider parameter range with controllable interaction between the spins of the nearest-neighbor atoms.Ultracold atoms with two hyperfine internal states in optical lattices are proposed to demonstrate a two-dimensional spin-$1/2$ model under a transverse effective staggered magnetic field. The transverse magnetic field is produced by a Raman process and can be modulated by the intensities of the additional light fields. This optical lattice protocol can investigate magnetic quantum phenomena induced by the effective staggered magnetic field in a wider parameter range with controllable interaction between the spins of the nearest-neighbor atoms.

Physical Review AApr 18, 20135 citations

Ultracold atoms with two hyperfine internal states in optical lattices are proposed to demonstrate a two-dimensional spin-

1/2

model under a transverse effective staggered magnetic field. The transverse magnetic field is produced by a Raman process and can be modulated by the intensities of the additional light fields. This optical lattice protocol can investigate magnetic quantum phenomena induced by the effective staggered magnetic field in a wider parameter range with controllable interaction between the spins of the nearest-neighbor atoms.