Ground-State Properties of Superfluid Fermi Gas in Fourier-Synthesized Optical Lattices
CHEN Yan1**, ZHANG Ke-Zhi1, WANG Xiao-Liang1, CHEN Yong2,3
1School of Physics and Electromechanical Engineering, Hexi University, Zhangye 734000 2Center of Soft Matter Physics and its Applications, Beihang University, Beijing 100191 3School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191
Abstract：By employing the balance condition between the lattice potential and the interatomic interaction, we study the ground state solutions of superfluid Fermi gases in Fourier-synthesized (FS) optical lattices. The average energy of the ground state, the atoms number, and the atom density distribution of the Fermi system are analytically derived along the Bose–Einstein condensation (BEC) side to the Bardeen–Cooper–Schrieffer (BCS) side. We analyze the properties of ground state solutions at both the BEC limit and unitarity in FS optical lattices. It is found that the relative phase α between the two lattice harmonics impacts greatly on the properties of the ground state of the superfluid Fermi gas. Especially in the BCS limit, when α=π/2, the average energy presents an exponential form with the increase of the potential depth of the lattice harmonics v2. Meanwhile, there exits a minimal value. Moreover, due to the Fermi pressure, the atom density distribution at unitarity is more outstretched than that in the BEC limit. The average energy at unitarity is apparently larger than that in the BEC limit. The properties of the ground state solution exhibit very different behaviors when the system transits from the BEC side to the BCS side.
2014, Vol. 31 
