Experimental evidence for Efimov quantum states Conference Paper

Author(s): Nägerl, Hanns C; Kraemer, Tobias; Mark, Michael J; Waldburger, Philipp; Danzl, Johannes G; Engeser, Bastian; Lange, Adam D; Pilch, Karl; Jaakkola, Antti; Chin, Cheng; Grimm, Rudolf
Title: Experimental evidence for Efimov quantum states
Abstract: Three interacting particles form a system which is well known for its complex physical behavior. A landmark theoretical result in few-body quantum physics is Efimov's prediction of a universal set of weakly bound trimer states appearing for three identical bosons with a resonant two-body interaction [1, 2]. Surprisingly, these states even exist in the absence of a corresponding two-body bound state and their precise nature is largely independent of the particular type of the two-body interaction potential. Efimov's scenario has attracted great interest in many areas of physics; an experimental test however has not been achieved. We report the observation of an Efimov resonance in an ultracold thermal gas of cesium atoms [3]. The resonance occurs in the range of large negative two-body scattering lengths and arises from the coupling of three free atoms to an Efimov trimer. We observe its signature as a giant three-body recombination loss when the strength of the two-body interaction is varied near a Feshbach resonance. This resonance develops into a continuum resonance at non-zero collision energies, and we observe a shift of the resonance position as a function of temperature. We also report on a minimum in the recombination loss for positive scattering lengths, indicating destructive interference of decay pathways. Our results confirm central theoretical predictions of Efimov physics and represent a starting point from which to explore the universal properties of resonantly interacting few-body systems.
Keywords: Bose-Einstein condensation; Three-body recombination; Feshbach resonances; ultracold molecules; Efimov states; Resonant scattering
Conference Title: ICAP: International Conference on Atomic Physics
Volume: 869
Conference Dates: July 16 -21, 2006
Conference Location: Innsbruck, Austria
ISBN: 978-073540367-3
Publisher: AIP  
Date Published: 2006-01-01
Start Page: 269
End Page: 277
DOI: 10.1063/1.2400657
Notes: We thank E. Braaten, C. Greene, B. Esry, H. Hammer, and T. Köhl er for many stimulat- ing and fruitful discussions and E. Kneringer for support re garding the data analysis. We acknowledge support by the Austrian Science Fund (FWF) with in Spezialforschungs- bereich 15 and within the Lise Meitner program, and by the Eur opean Union in the frame of the TMR networks “Cold Molecules” and “FASTNet”. M.M. is s upported within the Doktorandenprogramm of the Austrian Academy of Sciences.
Open access: yes (repository)