Test of the Universality of the Three-Body Efimov Parameter at Narrow Feshbach Resonances

Sanjukta Roy (1) , Manuelle Landini (1) , Andreas Trenkwalder (1) , Giulia Semeghini (1) , Giacomo Spagnolli (1) , Andrea Simoni (2) , Marco Fattori (1) , Massimo Inguscio (1) , Giovanni Modugno (1)

1 LENS - European Laboratory for Non-Linear Spectroscopy
2 IPR - Institut de Physique de Rennes

We measure the critical scattering length for the appearance of the first three-body bound state, or Efimov three-body parameter, at seven different Feshbach resonances in ultracold 39K atoms. We study both intermediate and narrow resonances, where the three-body spectrum is expected to be determined by the nonuniversal coupling of two scattering channels. Instead, our observed ratio of the three-body parameter with the van der Waals radius is approximately the same universal ratio as for broader resonances. This unexpected observation suggests the presence of a new regime for three-body scattering at narrow resonances.

Mots clés: efimov states feshbach resonances ultracold atoms

Domaines: Physique Atomique [physics.atom-ph]; Physique Quantique [quant-ph]; Gaz Quantiques [cond-mat.quant-gas]

Sanjukta Roy, Manuelle Landini, Andreas Trenkwalder, Giulia Semeghini, Giacomo Spagnolli, et al.. Test of the Universality of the Three-Body Efimov Parameter at Narrow Feshbach Resonances. Physical Review Letters, 2013, 111 (5), pp.053202-1-5. ⟨10.1103/PhysRevLett.111.053202⟩. ⟨hal-00976044⟩