Cooper Pairing in Ultracold K-40 Using Feshbach Resonances

TL;DR

This paper proposes using Feshbach resonances in ultracold K-40 atoms to facilitate Cooper pairing, potentially enabling the creation of a degenerate Fermi gas with superfluid properties.

Contribution

It identifies specific Feshbach resonances in K-40 that can induce attractive interactions necessary for Cooper pairing in ultracold gases.

Findings

Broad resonance at 196 gauss for s-wave pairing

Additional resonance at 191 gauss for p-wave pairing

Feasibility of creating a Cooper-paired Fermi gas with current technology

Abstract

We point out that the fermionic isotope K-40 is a likely candidate for the formation of Cooper pairs in an ultracold atomic gas. Specifically, in an optical trap that simultaneously traps the spin states |9/2,-9/2> and |9/2,-7/2>, there exists a broad magnetic field Feshbach resonance at B = 196 gauss that can provide the required strong attractive interaction between atoms. An additional resonance, at B = 191 gauss, could generate p-wave pairing between identical |9/2,-7/2> atoms. A Cooper-paired degenerate Fermi gas could thus be constructed with existing ultracold atom technology.