Multiple period states of the superfluid Fermi gas in an optical lattice

Year: 2016

Authors: Yoon S., Dalfovo F., Nakatsukasa T., Watanabe G.

Autors Affiliation: APCTP, Pohang 37673, Gyeongbuk, South Korea; KIAS, Quantum Universe Ctr, Seoul 02455, South Korea; Univ Trento, INO CNR BEC Ctr, I-38123 Povo, Italy; Univ Trento, Dept Phys, I-38123 Povo, Italy; Univ Tsukuba, Ctr Computat Sci, Tsukuba, Ibaraki 3058577, Japan; RIKEN Nishina Ctr, Wako, Saitama 3510198, Japan; POSTECH, Dept Phys, Pohang 37673, Gyeongbuk, South Korea; Inst for Basic Sci Korea, Ctr Theoret Phys Complex Syst, Daejeon 34051, South Korea; UST, 217 Gajeong Ro, Daejeon 34113, South Korea.

Abstract: We study multiple period states of a two-component unpolarized superfluid Fermi gas in an optical lattice along the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensate (BEC) crossover. The existence of states whose period is a multiple of the lattice spacing is a direct consequence of the nonlinear behavior of the gas, which is due to the presence of the order parameter associated with superfluidity. By solving Bogoliubov-de Gennes equations for a superfluid flow with finite quasimomentum, we find that, in the BCS side of the crossover, the multiple period states can be energetically favorable compared to the normal Bloch states and their survival time against dynamical instability drastically increases, suggesting that these states can be accessible in current experiments, in sharp contrast to the situation in BECs.

Journal/Review: NEW JOURNAL OF PHYSICS

Volume: 18      Pages from: 23011-1  to: 23011-10

More Information: We acknowledge P Fulde, M Horikoshi, M Modugno, and C J Pethick for helpful discussions. This work was supported by the Max Planck Soc iety, MEST of Korea, Gyeongsangbuk-Do, Pohang City, for the support of the JRG at APCTP, by Basic Science Research Program through NRF by MEST (Grant No. 2012R1A1A2008028), by Project Code (IBS-R024-D1), and by JSPS KAKENHI (Grant No. 24105006). FD acknowledges the support of ERC, through the QGBE grant, and of the Provincia Autonoma di Trento. Part of calculations were performed on RICC in RIKEN.
KeyWords: BCS-BEC crossover; optical lattices; superfluidity; nonlinear phenomena
DOI: 10.1088/1367-2630/18/2/023011

Citations: 3
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