Superfluid properties of ultracold fermionic atoms in two-dimensional optical lattices

昌久 古賀, Akihisa Koga

Yusuke Fujihara, Akihisa Koga, Norio Kawakami

Ya-Jie Wu, Ning Li, Su-Peng Kou

Yusuke Fujihara, Akihisa Koga, Norio Kawakami

We investigate two-component ultracold fermionic atoms with attractive interactions trapped in a two-dimensional optical lattice at zero temperature. By introducing a superfluid trial state with spatially modulated order parameters, we perform the variational Monte Carlo simulations to treat the correlation effects beyond mean-field treatments. It is shown that there appears a strong tendency to the formation of a density wave state in the regions with specific values of local atom density. We then analyze two kinds of perturbations to the superfluid state and show that a coexisting state of superfluid and density wave ordering, a sort of supersolid state, can be stabilized. It is discussed how the trap potential and the resulting spatial modulation of the superfluid state affect the momentum distributions and the noise correlation functions.

J. K. Chin, David E. Miller, Yingmei Liu +5 more

Pierfrancesco Buonsante, Francesco Massel, Vittorio Penna +1 more

In the present communication, we describe the properties induced by disorder on an ultracold gas of bosonic atoms loaded into a two-dimensional optical lattice with global confinement ensured by a parabolic potential. Our analysis is centred on the spatial distribution of the various phases, focusing particularly on the superfluid properties of the system as a function of external parameters and disorder amplitude. In particular, it is shown how disorder can suppress superfluidity, while partially preserving the system coherence.