Emergent s-wave interactions in orbitally active quasi-two-dimensional Fermi gases

Abstract

<p>We investigate the scattering properties and bound states of a quasi-two-dimensional (Q2D) spin-polarized Fermi gas near a 𝑝-wave Feshbach resonance. Strong confinement promotes the out-of-plane spatial wave function to an orbital degree of freedom with an energetic gap. Employing radio-frequency (rf) spectroscopy, we observe both power-law scaling and the dimensional-crossover feature that are indicative of an emergent 𝑠-wave interaction channel. Additionally, we demonstrate the formation of two types of low-energy dimers, possessing either 𝑠-wave or 𝑝-wave symmetry, through rf spin-flip association from an orbital mixture. Our observations are compared to predictions from a Q2D scattering model that incorporates exchange-antisymmetric orbital pair wave functions. These findings underscore how gapped orbital degrees of freedom can control scattering symmetry in strongly confined ultracold gases.<br></p>