  We investigate the attractive Hubbard model in infinite spatial dimensions by
means of dynamical mean-field theory. Using a continuous-time Monte Carlo
algorithm in the Nambu formalism as an impurity solver, we directly deal with
the superfluid phase in the population imbalanced system. By calculating the
superfluid order parameter, the magnetization, and the density of states, we
discuss how the polarized superfluid state is realized in the attractive
Hubbard model at quarter filling. We find that a drastic change in the density
of states is induced by spin imbalanced populations in the superfluid state.

Quantum Gases