We present lattice results for spin- $1∕2$ fermions at unitarity, where the effective range of the interaction is zero and the scattering length is infinite. We measure the spatial coherence of difermion pairs for a system of 6, 10, 14, 18, 22, 26 particles with equal numbers of up and down spins in a periodic cube. Using Euclidean time projection, we analyze ground-state properties and transient behavior due to low-energy excitations. At asymptotically large values of $t$ we see long-range order consistent with spontaneously broken U(1) fermion-number symmetry and a superfluid ground state. At intermediate times we see exponential decay in the $t$ -dependent signal due to an unknown low-energy excitation. We probe this low-energy excitation further by calculating two-particle correlation functions. We find that the excitation has the properties of a chain of particles extending across the periodic lattice.We present lattice results for spin-$1∕2$ fermions at unitarity, where the effective range of the interaction is zero and the scattering length is infinite. We measure the spatial coherence of difermion pairs for a system of 6, 10, 14, 18, 22, 26 particles with equal numbers of up and down spins in a periodic cube. Using Euclidean time projection, we analyze ground-state properties and transient behavior due to low-energy excitations. At asymptotically large values of $t$ we see long-range order consistent with spontaneously broken U(1) fermion-number symmetry and a superfluid ground state. At intermediate times we see exponential decay in the $t$-dependent signal due to an unknown low-energy excitation. We probe this low-energy excitation further by calculating two-particle correlation functions. We find that the excitation has the properties of a chain of particles extending across the periodic lattice.

arXiv:cond-mat/0606706Physical Review BApr 3, 200718 citations

Collective excitations in superfluid Fermi systems

Victor Nikolaevich Popov

Cambridge University Press eBooksJan 7, 19880 citations

Collective excitations in a fermion-fermion mixture with different Fermi surfaces

Lan Yin

In this paper, collective excitations in a homogeneous fermion-fermion mixture with different Fermi surfaces are studied. In the Fermi liquid phase, the zero-sound velocity is found to be larger than the largest Fermi velocity. With attractive interactions, the superfluid phase appears below a critical temperature, and the phase mode is the low-energy collective excitation. The velocity of the phase mode is significantly different from the zero-sound velocity. The difference between the two velocities may serve as a tool to detect the superfluid phase.In this paper, collective excitations in a homogeneous fermion-fermion mixture with different Fermi surfaces are studied. In the Fermi liquid phase, the zero-sound velocity is found to be larger than the largest Fermi velocity. With attractive interactions, the superfluid phase appears below a critical temperature, and the phase mode is the low-energy collective excitation. The velocity of the phase mode is significantly different from the zero-sound velocity. The difference between the two velocities may serve as a tool to detect the superfluid phase.

arXiv:cond-mat/0309344Physical Review ANov 3, 20031 citation

Fermionic Superfluidity

WORLD SCIENTIFIC eBooksJul 1, 20100 citations

Dissipative superfluids, from cold atoms to quark matter

Massimo Mannarelli, Cristina Manuel

Some results about dissipative processes in superfluids are presented. We focus on fermionic superfluidity and restrict our analysis to the contribution of phonons to bulk viscosity, shear viscosity and thermal conductivity. At sufficiently low temperatures phonons give the dominant contribution to the transport coefficients if all the other low energy excitation of the system are gapped. We first consider a system of cold fermionic atoms close to the unitarity limit. Then we turn to the superfluid phase of quark matter that may be realized at high baryonic density.Some results about dissipative processes in superfluids are presented. We focus on fermionic superfluidity and restrict our analysis to the contribution of phonons to bulk viscosity, shear viscosity and thermal conductivity. At sufficiently low temperatures phonons give the dominant contribution to the transport coefficients if all the other low energy excitation of the system are gapped. We first consider a system of cold fermionic atoms close to the unitarity limit. Then we turn to the superfluid phase of quark matter that may be realized at high baryonic density.

arXiv:0910.4326Lectures given atOct 22, 20092 citations

Oscillatory-like expansion of a Fermionic superfluid

Xiao-Qiong Wang, Yu-Ping Wu, Xiang-Pei Liu +7 more

arXiv:1702.08326中国科学通报：英文版Oct 25, 20198 citations

We present lattice results for spin-

1∕2

fermions at unitarity, where the effective range of the interaction is zero and the scattering length is infinite. We measure the spatial coherence of difermion pairs for a system of 6, 10, 14, 18, 22, 26 particles with equal numbers of up and down spins in a periodic cube. Using Euclidean time projection, we analyze ground-state properties and transient behavior due to low-energy excitations. At asymptotically large values of

t

we see long-range order consistent with spontaneously broken U(1) fermion-number symmetry and a superfluid ground state. At intermediate times we see exponential decay in the

t

-dependent signal due to an unknown low-energy excitation. We probe this low-energy excitation further by calculating two-particle correlation functions. We find that the excitation has the properties of a chain of particles extending across the periodic lattice.