Observation of an Efimov spectrum in an atomic system

Year: 2009

Authors: Zaccanti M., Deissler B., D’Errico C., Fattori M., Jona-Lasinio M., Muller S., Roati G., Inguscio M., Modugno G.

Autors Affiliation: LENS and Physics Department, Università di Firenze, and INFM-CNR, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy;
Museo Storico della Fisica e Centro Studi e Ricerche ‘E. Fermi’, 00184 Roma, Italy;
Physikalisches Institut, Universität Stuttgart, 70550 Stuttgart, Germany

Abstract: In 1970, Vitaly Efimov predicted that three quantum particles subjected to a resonant pair-wise interaction can join into an infinite number of loosely bound states, even if each pair of particles cannot bind. The properties of these aggregates, such as the peculiar geometric scaling of their energy spectrum, are universal, that is, independent of the microscopic details of their components. Despite an extensive search in many different physical systems, including atoms, molecules and nuclei, the characteristic spectrum of Efimov trimer states has not been observed so far. Here, we report on the discovery of two bound trimer states of potassium atoms very close to the Efimov scenario, which we reveal by studying three-particle collisions in an ultracold gas. Our observation provides the first evidence of an Efimov spectrum and enables a direct test of its scaling behaviour, providing potentially general insights into the physics of few-body systems.

Journal/Review: NATURE PHYSICS

Volume: 5 (8)      Pages from: 586  to: 591

More Information: We thank P. Massignan and H. Stoof for motivating this work and for discussions. We acknowledge also B. D. Esry, J.P. D\’Incao, R. Grimm and co-workers, and A. Simoni for discussions. We are grateful to S. Bartalini and G. Thalhammer for technical help. This work has been supported by CNR within the EUROCORES Programme EuroQUAM of the European Science Foundation, by the European Research Council through the Starting Grant \’QUPOL\’ and by the Italian MIUR (PRIN2006 programme).
KeyWords: Large scattering length; 3-body recombination; Interacting particles; Feshbach resonances; Energy-levels; Ultracold; Collisions; States; Limit
DOI: 10.1038/NPHYS1334

Citations: 324
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