Reshaped Three-Body Interactions and the Observation of an Efimov State in the Continuum

Abstract

Efimov trimers are exotic three-body quantum states that emerge from the different types of three-body continua in the vicinity of two-atom Feshbach resonances. In particular, as the strength of the interaction is decreased to a critical point, an Efimov state merges into the atom-dimer threshold and eventually dissociates into an unbound atom-dimer pair. Here we explore the Efimov state in the vicinity of this critical point using coherent few-body spectroscopy in ${}^7$Li atoms using a narrow two-body Feshbach resonance. Contrary to the expectation, we find that the ${}^7$Li Efimov trimer does not immediately dissociate when passing the threshold, and survives as a metastable state embedded in the atom-dimer continuum. We identify this behavior with a universal phenomenon related to the emergence of a repulsive interaction in the atom-dimer channel which reshapes the three-body interactions in any system characterized by a narrow Feshbach resonance. Specifically, our results shed light on the nature of ${}^7$Li Efimov states and provide a path to understand various puzzling phenomena associated with them.

17 pages, 12 figures. arXiv admin note: text overlap with arXiv:2004.02723

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Cited by in corpus (10)

• Three-body forces and Efimov physics in nuclei and atoms
• Emergent inflation of the Efimov spectrum under three-body spin-exchange interactions
• Observation of a Halo Trimer in an Ultracold Bose-Fermi Mixture
• Closed-channel parameters of Feshbach resonances
• Density effects on the interferometry of Efimov states by modulating magnetic fields
• Accurate simulation of Efimov physics in ultracold atomic gases with realistic three-body multichannel interactions
• Universal spectrum of isolated three-body resonances
• Characterization of Feshbach resonances in ${}^6\mathrm{Li}{-}^7\mathrm{Li}$ using improved interaction potentials
• Universality in Ionic Three-body Systems Near an Ion-atom Feshbach Resonance
• Stabilization of three-body resonances to bound states in a continuum