Finite-temperature effects on a triatomic Efimov resonance in ultracold cesium

TL;DR

This study investigates how finite temperature influences the position of Efimov resonances in ultracold cesium gases, revealing a temperature-dependent shift linked to the finite range of atomic interactions and emphasizing the importance for precise experimental measurements.

Contribution

It provides a detailed experimental and theoretical analysis of finite-temperature effects on Efimov resonances, highlighting the energy dependence of the three-body parameter due to van der Waals interactions.

Findings

Resonance shifts with temperature are consistent with a universal behavior.

Finite-range effects of van der Waals interactions influence the three-body parameter.

Theoretical models incorporating van der Waals forces accurately describe the observed shifts.

Abstract

We report a thorough investigation of finite-temperature effects on three-body recombination near a triatomic Efimov resonance in an ultracold gas of cesium atoms. Our measurements cover a wide range from a near-ideal realization of the zero-temperature limit to a strongly temperature-dominated regime. The experimental results are analyzed within a recently introduced theoretical model based on a universal zero-range theory. The temperature-induced shift of the resonance reveals a contribution that points to an energy-dependence of the three-body parameter. We interpret this contribution in terms of the finite range of the van der Waals interaction in real atomic systems and we quantify it in an empirical way based on length scale arguments. A universal character of the corresponding resonance shift is suggested by observations related to other Efimov resonances and the comparison with a theoretical finite-temperature approach that explicitly takes the van der Waals interaction into account. Our findings are of importance for the precise determination of Efimov resonance positions from experiments at finite temperatures.