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Collective excitations across the BCS-BEC crossover induced by a synthetic Rashba spin-orbit coupling by Vyasanakere, Jayantha P.; Shenoy, Vijay B. is a scholarly article available to read on EtoBox.

What is Collective excitations across the BCS-BEC crossover induced by a synthetic Rashba spin-orbit coupling about?

Synthetic non-Abelian gauge fields in cold atom systems produce a Rashba spin-orbit interaction described by a vector $\blam = (\lambda_x, \lambda_y, \lambda_z)$. It was recently shown [Phys. Rev. B 84, 014512 (2011)] that on increasing $\lambda = |\blam|$, fermions at a finite density $\rho\approx\kf^3$ evolve to a BEC like state even in the presence of a weak attractive interaction (described by a scattering length $\as$). The BEC obtained at large spin-orbit coupling ($\lambda \gg k_F$) is a condensate of rashbons -- novel bosonic bound pairs of fermions whose properties are determined solely by the gauge field. Here we study the collective excitations of such superfluids by constructing a Gaussian theory using functional integral methods. We derive explicit expressions for superfluid phase stiffness, sound speed and mass of the Anderson-Higgs boson that are valid for any $\blam$ and scattering length. We find that at finite $\lambda$, the phase stiffness is always lower than that set by the density of particles, consistent with earlier work[arXiv:1110.3565] which attributed this to the lack of Galilean invariance of the system at finite $\lambda$. We show that there is an emerg

Author

Vyasanakere, Jayantha P.; Shenoy, Vijay B.

Published

2012

Language

EN