Evidence for Universal Four-Body States Tied to an Efimov Trimer

TL;DR

This paper provides experimental evidence for universal four-body states linked to Efimov trimers, confirming theoretical predictions and expanding understanding of few-body quantum phenomena in ultracold gases.

Contribution

First experimental observation of universal four-body states connected to Efimov trimers in an ultracold cesium gas.

Findings

Resonant enhancement of four-body recombination rates

Strong evidence for four-body states tied to Efimov trimers

Confirmation of theoretical universal relations in few-body physics

Abstract

We report on the measurement of four-body recombination rate coefficients in an atomic gas. Our results obtained with an ultracold sample of cesium atoms at negative scattering lengths show a resonant enhancement of losses and provide strong evidence for the existence of a pair of four-body states, which is strictly connected to Efimov trimers via universal relations. Our findings confirm recent theoretical predictions and demonstrate the enrichment of the Efimov scenario when a fourth particle is added to the generic three-body problem.