We theoretically study the relaxation of high energy single particle excitations into molecules in a system of attractive fermions in an optical lattice, both in the superfluid and the normal phase. In a system characterized by an interaction scale U and a tunneling rate t, we show that the relaxation rate scales as ∼Ctexp[-αU(2)/t(2)ln(U/t)] in the large U/t limit. We obtain explicit expressions for the temperature and density dependent exponent α, both in the low temperature superfluid phase and the high temperature phase with pairing but no coherence between the molecules. We find that the relaxation rate decreases both with temperature and deviation of the fermion density from half filling. We show that quasiparticle and phase degrees of freedom are effectively decoupled within experimental time scales allowing for observation of ordered states even at high total energy of the system.We theoretically study the relaxation of high energy single particle excitations into molecules in a system of attractive fermions in an optical lattice, both in the superfluid and the normal phase. In a system characterized by an interaction scale U and a tunneling rate t, we show that the relaxation rate scales as ∼Ctexp[-αU(2)/t(2)ln(U/t)] in the large U/t limit. We obtain explicit expressions for the temperature and density dependent exponent α, both in the low temperature superfluid phase and the high temperature phase with pairing but no coherence between the molecules. We find that the relaxation rate decreases both with temperature and deviation of the fermion density from half filling. We show that quasiparticle and phase degrees of freedom are effectively decoupled within experimental time scales allowing for observation of ordered states even at high total energy of the system.

arXiv:1105.1778Physical Review LettersSep 27, 20118 citations

Fermionic Superfluidity

WORLD SCIENTIFIC eBooksJul 1, 20100 citations

Condensate of excitations in moving superfluids

Evgeni E. Kolomeitsev, Dmitry N. Voskresensky

A possibility of the condensation of excitations with a non-zero momentum in rectilinearly moving and rotating superfluid bosonic and fermionic (with Cooper pairing) media is considered in terms of a phenomenological order-parameter functional at zero and non-zero temperature. The results might be applicable to the description of bosonic systems like superfluid $^4$ He, ultracold atomic Bose gases, charged pion and kaon condensates in rotating neutron stars, and various superconducting fermionic systems with pairing, like proton and color-superconducting components in compact stars, metallic superconductors, and neutral fermionic systems with pairing, like the neutron component in compact stars and ultracold atomic Fermi gases. Order parameters of the "mother" condensate in the superfluid and the new condensate of excitations, corresponding energy gains, critical temperatures and critical velocities are found.A possibility of the condensation of excitations with a non-zero momentum in rectilinearly moving and rotating superfluid bosonic and fermionic (with Cooper pairing) media is considered in terms of a phenomenological order-parameter functional at zero and non-zero temperature. The results might be applicable to the description of bosonic systems like superfluid $^4$He, ultracold atomic Bose gases, charged pion and kaon condensates in rotating neutron stars, and various superconducting fermionic systems with pairing, like proton and color-superconducting components in compact stars, metallic superconductors, and neutral fermionic systems with pairing, like the neutron component in compact stars and ultracold atomic Fermi gases. Order parameters of the "mother" condensate in the superfluid and the new condensate of excitations, corresponding energy gains, critical temperatures and critical velocities are found.

arXiv:1611.05093Progress of Theoretical and Experimental PhysicsNov 15, 20163 citations

Fermionic Superfluidity: Cooper Pairing

Andreas Schmitt

Lecture notes in physicsJun 13, 20140 citations

Superfluid Expansion of a Rotating Fermi Gas

Christian H. Schunck, Martin W. Zwierlein, André Schirotzek +1 more

We study the expansion of a rotating, superfluid Fermi gas. The presence and absence of vortices in the rotating gas are used to distinguish the superfluid and normal parts of the expanding cloud. We find that the superfluid pairs survive during the expansion until the density decreases below a critical value. Our observation of superfluid flow in the expanding gas at 1/kFa=0 extends the range where fermionic superfluidity has been studied to densities of 1.2x10(11) cm(-3), about an order of magnitude lower than any previous study.We study the expansion of a rotating, superfluid Fermi gas. The presence and absence of vortices in the rotating gas are used to distinguish the superfluid and normal parts of the expanding cloud. We find that the superfluid pairs survive during the expansion until the density decreases below a critical value. Our observation of superfluid flow in the expanding gas at 1/kFa=0 extends the range where fermionic superfluidity has been studied to densities of 1.2x10(11) cm(-3), about an order of magnitude lower than any previous study.

Bulletin of the American Physical SocietyMay 20, 20060 citations

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He, ultracold atomic Bose gases, charged pion and kaon condensates in rotating neutron stars, and various superconducting fermionic systems with pairing, like proton and color-superconducting components in compact stars, metallic superconductors, and neutral fermionic systems with pairing, like the neutron component in compact stars and ultracold atomic Fermi gases. Order parameters of the "mother" condensate in the superfluid and the new condensate of excitations, corresponding energy gains, critical temperatures and critical velocities are found.