2005/12/31 by T. Kraemer, M. Mark, Manfred J. Mark +13 · 1,013 citations
Physics and Astronomy · #Advanced Frequency and Time Standards #Atomic physics #Caesium #Cold Atom Physics and Bose-Einstein Condensates #Nuclear physics #Physics #Quantum #Quantum mechanics #Quantum, superfluid, helium dynamics #Ultracold atom #cond-mat.other
paper · pdf · doi:10.1038/nature04626
published in Nature 440(7082), 315-318 (Nature Portfolio) · 18 pages, 3 figures
arxiv created 2006/02/02 · openalex publication_date 2006/03/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Systems of three interacting particles are notorious for their complex physical behavior. A landmark theoretical result in few-body quantum physics is Efimov's prediction of a universal set of bound trimer states appearing for three identical bosons with a resonant two-body interaction. Counterintuitively, these states even exist in the absence of a corresponding two-body bound state. Since the formulation of Efimov's problem in the context of nuclear physics 35 years ago, it has attracted great interest in many areas of physics. However, the observation of Efimov quantum states has remained an elusive goal. Here we report the observation of an Efimov resonance in an ultracold gas of cesium atoms. The resonance occurs in the range of large negative two-body scattering lengths, arising from the coupling of three free atoms to an Efimov trimer. Experimentally, we observe its signature as a giant three-body recombination loss when the strength of the two-body interaction is varied. We also detect 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 with which to explore the universal properties of resonantly interacting few-body systems. While Feshbach resonances have provided the key to control quantum-mechanical interactions on the two-body level, Efimov resonances connect ultracold matter to the world of few-body quantum phenomena.