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Observation of Efimov Universality across a Nonuniversal Feshbach Resonance in K-39

TitleObservation of Efimov Universality across a Nonuniversal Feshbach Resonance in K-39
Publication TypeJournal Article
Year of Publication2020
AuthorsX. Xie, M. J. Van de Graaff, R. Chapurin, M. D. Frye, J. M. Hutson, J. P. D'Incao, P. S. Julienne, J. Ye, and E. A. Cornell
JournalPhys. Rev. Lett.
Volume125
Date Publisheddec
ISSN0031-9007
Abstract

We study three-atom inelastic scattering in ultracold K-39 near a Feshbach resonance of intermediate coupling strength. The nonuniversal character of such resonance leads to an abnormally large Efimov absolute length scale and a relatively small effective range r(e), allowing the features of the 39 K Efimov spectrum to be better isolated from the short-range physics. Meticulous characterization of and correction for finite-temperature effects ensure high accuracy on the measurements of these features at large-magnitude scattering lengths. For a single Feshbach resonance, we unambiguously locate four distinct features in the Efimov structure. Three of these features form ratios that obey the Efimov universal scaling to within 10%, while the fourth feature, occurring at a value of scattering length closest to r(e), instead deviates from the universal value.

DOI10.1103/PhysRevLett.125.243401