Observation of "broad" d-wave Feshbach resonances with a triplet structure

TL;DR

This paper reports the experimental observation and characterization of broad d-wave Feshbach resonances with a triplet structure in an ultracold Rb mixture, highlighting their potential for simulating complex many-body systems.

Contribution

First experimental observation of broad d-wave Feshbach resonances with triplet structure in an ultracold Rb mixture, supported by multichannel quantum-defect theory analysis.

Findings

Observation of two broad d-wave Feshbach resonances

Resolved triplet structure explained by spin-spin interaction

Identification of temperature and time requirements for resonance observation

Abstract

High partial-wave ($l\ge2$) Feshbach resonance (FR) in an ultracold mixture of $^{85}$Rb-$^{87}$Rb atoms is investigated experimentally aided by a partial-wave insensitive analytic multichannel quantum-defect theory (MQDT). Two "broad" resonances from coupling between d-waves in both the open and closed channels are observed and characterized. One of them shows a fully resolved triplet structure with splitting ratio well explained by the perturbation to the closed channel due to interatomic spin-spin interaction. These tunable "broad" d-wave resonances, especially the one in the lowest-energy open channel, could find important applications in simulating d-wave coupling dominated many-body systems. In addition, we find that there is generally a time and temperature requirement, associated with tunneling through the angular momentum barrier, to establish and observe resonant coupling in nonzero partial waves.