Accurate simulation of Efimov physics in ultracold atomic gases with realistic three-body multichannel interactions

TL;DR

This paper presents a comprehensive numerical method for simulating Efimov physics in ultracold alkali-metal gases, accurately incorporating multichannel interactions and resolving previous theoretical-experimental discrepancies.

Contribution

The authors develop a self-contained computational approach that rigorously includes multichannel effects in three-body problems, improving the accuracy of Efimov physics simulations.

Findings

Accurately reproduces molecular energy levels using realistic potentials.

Resolves longstanding theory-experiment disagreement for ${}^7$Li Efimov parameter.

Shows strong sensitivity of recombination rates to spin structure.

Abstract

We give a detailed and self-contained description of a recently developed theoretical and numerical method for the simulation of three identical bosonic alkali-metal atoms near a Feshbach resonance, where the Efimov effect is induced. The method is based on a direct construction of the off-shell two-body transition matrix from exact eigenfunctions of the embedded two-body Hamiltonians, obtained using realistic parameterizations of the interaction potentials which accurately reproduce the molecular energy levels. The transition matrix is then inserted into the appropriate three-body integral equations, which may be efficiently solved on a computer. We focus especially on the power of our method in including rigorously the effects of multichannel physics on the three-body problem, which are usually accounted for only by various approximations. We demonstrate the method for ${}^7$Li, where we recently showed that a correct inclusion of this multichannel physics resolves the long-standing disagreement between theory and experiment regarding the Efimovian three-body parameter. We analyze the Efimovian enhancement of the three-body recombination rate on both sides of the Feshbach resonance, revealing strong sensitivity to the spin structure of the model thus indicating the prevalence of three-body spin-exchange physics. Finally, we discuss an extension of our methodology to the calculation of three-body bound-state energies.