Beyond Born-Oppenheimer approximation in ultracold atomic collisions

TL;DR

This paper investigates deviations from the Born-Oppenheimer approximation in ultracold potassium collisions, identifying new resonances and improving inter-atomic potential models, revealing differences between homonuclear and heteronuclear cases.

Contribution

It introduces the first identification of unknown $d$-wave Feshbach resonances in potassium and demonstrates how Born-Oppenheimer corrections can be extracted from collisional data.

Findings

Discovery of three new $d$-wave Feshbach resonances.

Enhanced understanding of $^{39}$K inter-atomic potentials.

Evidence of significant differences between homo- and heteronuclear cases.

Abstract

We report on deviations beyond the Born-Oppenheimer approximation in the potassium inter-atomic potentials. Identifying three up-to-now unknown $d$-wave Feshbach resonances, we significantly improve the understanding of the $^{39}$K inter-atomic potentials. Combining these observations with the most recent data on known inter- and intra-isotope Feshbach resonances, we show that Born-Oppenheimer corrections can be determined from atomic collisional properties alone and that significant differences between the homo- and heteronuclear case appear.