The shear viscosity of superfluid 6Li

Non-equilibrium stimulation of superfluidity in trapped Fermi gases is discussed by analogy to the work of Eliashberg [G. M. Eliashberg, in "Nonequilibrium Superconductivity," edited by D. N. Langenberg and A. I. Larkin (North-Holland, New York, 1986)] on the microwave enhancement of superconductivity. Optical excitation of the fermions balanced by heat loss due to thermal contact with a boson bath and/or evaporative cooling enables stationary non-equilibrium states to exist. Such a state manifests as a shift of the quasiparticle spectrum to higher energies and this effectively raises the pairing transition temperature. As an illustration, we calculate the effective enhancement of Cooper pairing and superfluidity in both the normal and superfluid phases for a mixture of 87 Rb and 6 Li in the limit of small departure from equilibrium. It is argued that in experiment the desirable effect is not limited to such small perturbations and the effective enhancement of the pairing temperature may be quite large.

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“…The quasiparticle lifetime τ k for the normal fluid is estimated as τ k ≈ 3 µs for |ε k − ε F | ≃hω via the methods in Refs. [26,28].…”

Section: Numerical Resultsmentioning

confidence: 99%

Nonequilibrium enhancement of Cooper pairing in cold fermion systems

Robertson

Galitski

2009

Phys. Rev. A

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“…The experimental measurements of the attenuation of collective modes in ultracold fermion gases can determine whether the superfluid state is s -wave or p -wave, since in s -wave state the shear viscosity is constant at low temperatures [9,11], whereas in p -wave state all components are proportional inversely to temperature with powers of 2, 4 and 6.…”

Section: Shear Viscositymentioning

confidence: 99%

“…The shear and bulk viscosities of 6 Li in the weakcoupling limit, for temperatures near T c and zero have been calculated by Shahzamanian and Yavari for the swave superfluid [11,12]. They showed that the shear viscosity decreases as (1 − T /T c ) with temperature, when passing through the transition temperature, and goes to a constant at very low temperatures.…”

Section: Introductionmentioning

confidence: 99%

Shear viscosity of p-wave superfluid Fermi gas with weak interaction at low temperatures

Nasirimoghadam¹,

Aliabadi²,

Ali³

2016

Preprint

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The shear viscosity tensor of the superfluid Fermi gas in p -wave state with weak interaction is calculated at low temperatures, by using the Boltzmann equation approach. We consider the transition probabilities for the binary, decay and coalescence processes. We show that only the binary processes are dominated at low temperatures and the components of shear viscosity ηxy, ηxx, ηyy are proportional to (1/T ) 2 , and ηxz, ηyz and ηzz are proportional to (1/T ) 4 and (1/T ) 6 , respectively.

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“…We expressed ( ) χ p as a series of spherical harmonics in the polar angles 1 (11) by inserting (11) in (10) and integrate over y we have…”

Section: Collision Integralmentioning

confidence: 99%

“…The shear viscosity and the second viscosity of superfluid 6 Li have been formulated in the scope of Boltzmann equation approach [10] [11]. The value of the shear viscosity decreases as ( )…”

Section: Introductionmentioning

confidence: 99%