Efimov Resonance and Three-Body Parameter in a Lithium-Rubidium Mixture

Area of Science:

• Ultracold atomic physics
• Quantum chemistry
• Few-body physics

Background:

• Collisional heating and three-body recombination are critical phenomena in ultracold atomic gases.
• Feshbach resonances provide a powerful tool to tune interatomic interactions.
• Heteronuclear Efimov resonances are predicted but experimentally challenging to observe.

Purpose of the Study:

• To investigate collisional heating and three-body recombination in a cold ^{7}Li-^{87}Rb mixture.
• To identify and characterize heteronuclear Efimov resonances.
• To develop a consistent model for Li-Rb molecular potentials and scattering properties.

Main Methods:

• Utilizing Feshbach spectroscopy near a broad resonance at 661 G.
• Analyzing enhanced three-body recombination rates at the high field slope.
• Developing a molecular potential model to explain Feshbach resonances across Li-Rb isotope mixtures.

Main Results:

• An enhanced three-body recombination rate was observed, interpreted as a heteronuclear Efimov resonance.
• A refined model for molecular potentials accurately describes known Feshbach resonances in Li-Rb mixtures.
• The scattering length of the observed Efimov state was determined to be -1870a_{0}.

Conclusions:

• The experimental observation of a heteronuclear Efimov resonance in ^{7}Li-^{87}Rb is reported.
• The developed molecular potential model offers a consistent explanation for Feshbach resonances in Li-Rb systems.
• The determined scattering length supports the universality of the three-body parameter in heteronuclear mixtures.