Associating emergent s-wave dimers along strongly confined directions of a spin-polarized Fermi gas

Scattering channels activated with orbital degrees of freedom provide new routes for exploring few- and many-body phenomena. Here, we prepare orbitally excited systems of spin-polarized fermionic potassium (40K) in quasi-two-dimensional (quasi-2D) confinement near a p-wave Feshbach resonance. Although interactions have three-dimensional p-wave symmetry at short range, orbital singlet wave functions in the confinement direction allow effective s-wave scattering in the quasi-2D plane.

We measure the binding energies of quasi-2D dimers using a radio-frequency (rf) spin-flip association protocol. Measurements are performed in two confinement geometries, whose common features demonstrate the appearance of emergent s-wave dimers as resulting from the hybridization of orbital bands with the p-wave dimer in the confinement direction. The results are compared to a model of quasi-2D scattering that includes band excitations.

In a second set of measurements, we study the strengths of resonantly enhanced interactions for each quasi-2D dimer by measuring how high-frequency rf transfer rates depend on magnetic field, lattice confinement, and population in the excited bands. The resulting atom-atom correlations are interpreted through a set of universal relations, revealing the 2D contact parameters. These results extend the paradigm previously established in quasi-one-dimensional systems [1], and provide a comprehensive framework for engineering exotic interactions with orbital dynamics.