Characterizing a narrow rotational p-wave Feshbach resonance

Feshbach resonances provide tunable p-wave interactions in ultracold atom systems, opening up the possibility to study unconventional many body states, such as topological superfluids. The route to chiral many body states is so far unclear, due to enhanced recombination loss that prevents a robust symmetry-breaking state. Here we present calculations and measurements of a narrow rotational p-wave Feshbach resonance between fermionic potassium 40 atoms in the hyperfine ground state, which is electron- and nuclear-spin polarized. The resonance exhibits an unusual coupling mechanism that selectively tunes the scattering phase of atom pairs colliding with M_L=+1 relative angular momentum, i.e. “right-handed” collisions. This leads to a weak interaction that splits p_x±ip_y states. Furthermore, no two-body loss is expected, and the lifetime of a degenerate gas in a bulk trap, where three-body loss should dominate, is measured to be on the order of seconds. We characterize elastic properties of the resonance by preparing triplet pairs of atoms in the lowest two bands of a 3D optical lattice. In the deep lattice limit, tunneling is negligible, creating an ensemble of isolated pairs. The confinement induced shift of the resonance is used to infer the differential magnetic moment between the open and closed channels. Finally, we extract the energy splitting of the resonance by associating dimer pairs using adiabatic field sweeps. Results are compared to coupled channel and pseudopotential models.