Efimov resonance position near a narrow Feshbach resonance in $^6$Li-$^{133}$Cs mixture

TL;DR

This study experimentally confirms that Efimov resonance positions near a narrow Feshbach resonance in a $^6$Li-$^{133}$Cs mixture are primarily determined by the resonance's properties rather than the van der Waals length, highlighting the influence of nearby resonances.

Contribution

The paper provides experimental validation of theoretical predictions that Efimov features near narrow Feshbach resonances depend mainly on resonance properties, using a three-channel model in a $^6$Li-$^{133}$Cs mixture.

Findings

Efimov resonance position is mainly dictated by resonance physics.

Van der Waals tail has minor influence on Efimov resonance position.

Nearby Feshbach resonances significantly alter the effective background scattering length.

Abstract

In the vicinity of a narrow Feshbach resonances Efimov features are expected to be characterized by the resonance's properties rather than the van der Waals length of the interatomic potential. Although this theoretical prediction is well-established by now, it still lacks experimental confirmation. Here, we apply our recently developed three-channel model [Yudkin and Khaykovich, Phys. Rev. A 103, 063303 (2021)] to the experimental result obtained in a mass-imbalanced $^6$Li-$^{133}$Cs mixture in the vicinity of the narrowest resonance explored to date [Johansen at. al. Nat. Phys. 13, 731 (2017)]. We confirm that the observed position of the Efimov resonance is dictated mainly by the resonance physics while the influence of the van der Waals tail of the interatomic potential is minor. We show that the resonance position is strongly influenced by the presence of another Feshbach resonance which significantly alters the effective background scattering length at the narrow resonance position.