Abstract
We propose a theoretical idea to reach the -wave superfluid phase in an ultracold Fermi gas. The key of our idea is that the pairing symmetry of a Fermi superfluid is fully dominated by the symmetry of the superfluid order parameter, which is essentially given by the product of a pair amplitude and a pairing interaction. Noting this, in our proposal, we first prepare a -wave pair amplitude not by using a -wave interaction, but by using the phenomenon that a -wave pair amplitude is induced in an -wave superfluid Fermi gas with antisymmetric spin-orbit interaction. In this case, although the system is still in the -wave superfluid state with the -wave superfluid order parameter, when one suddenly replaces the -wave interaction by an appropriate -wave one (which is possible in cold Fermi gases by using a Feshbach resonance technique), the product of the -wave interaction and the -wave pair amplitude that has already been prepared in the spin-orbit-coupled -wave superfluid state immediately gives a finite -wave superfluid order parameter. Thus, at least just after this manipulation, the system is in the -wave superfluid state, being characterized by the artificially produced -wave superfluid parameter. In this paper, to assess our idea, we evaluate the -wave pair amplitude in a spin-orbit-coupled -wave superfluid Fermi gas at . We determine the region where a large -wave pair amplitude is obtained in the phase diagram with respect to the strengths of the -wave pairing interaction and the spin-orbit coupling. We also discuss the accessibility of this optimal region on the viewpoint of the superfluid phase transition temperature. Since the achievement of a -wave superfluid Fermi gas is one of the most crucial issues in cold-atom physics, our proposal would be useful for this exciting challenge.
2 More- Received 14 April 2015
DOI:https://doi.org/10.1103/PhysRevA.92.013615
©2015 American Physical Society