Since the early days of quantum physics, the complex behavior of three interacting particles has been the subject of numerous experimental and theoretical studies. In a recent Letter to Nature, Kraemer et al. [Nature (London) 440, 315 (2006)] report on experimental ``evidence for Efimov quantum states'' in an ultracold gas of cesium atoms. Such quantum states refer to an infinite series of energy levels of three identical Bose particles, accumulating at the threshold for dissociation as the scattering length of each pair is tuned to infinity. Whereas the existence of a single Efimov state has been predicted for three helium atoms, earlier experimental studies concluded that this elusive state had not been found. In this paper we show by an intuitive argument and full numerical calculations that the helium and cesium experiments actually provide evidence of the same, ground state of this trimer spectrum, which the helium experimentalists and pioneering theoretical studies had not associated with Efimov's effect. Unlike the helium trimer, the observed $^{133}\mathrm{Cs}_{3}$ resonance refers to a Borromean molecular state. We discuss how as yet unobserved, excited Efimov quantum states might be detected in ultracold gases of $^{85}\mathrm{Rb}$ and of $^{133}\mathrm{Cs}$ at magnetic field strengths in the vicinity of $0.08\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ $(800\phantom{\rule{0.3em}{0ex}}\mathrm{G})$ .Since the early days of quantum physics, the complex behavior of three interacting particles has been the subject of numerous experimental and theoretical studies. In a recent Letter to Nature, Kraemer et al. [Nature (London) 440, 315 (2006)] report on experimental ``evidence for Efimov quantum states'' in an ultracold gas of cesium atoms. Such quantum states refer to an infinite series of energy levels of three identical Bose particles, accumulating at the threshold for dissociation as the scattering length of each pair is tuned to infinity. Whereas the existence of a single Efimov state has been predicted for three helium atoms, earlier experimental studies concluded that this elusive state had not been found. In this paper we show by an intuitive argument and full numerical calculations that the helium and cesium experiments actually provide evidence of the same, ground state of this trimer spectrum, which the helium experimentalists and pioneering theoretical studies had not associated with Efimov's effect. Unlike the helium trimer, the observed $^{133}\mathrm{Cs}_{3}$ resonance refers to a Borromean molecular state. We discuss how as yet unobserved, excited Efimov quantum states might be detected in ultracold gases of $^{85}\mathrm{Rb}$ and of $^{133}\mathrm{Cs}$ at magnetic field strengths in the vicinity of $0.08\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ $(800\phantom{\rule{0.3em}{0ex}}\mathrm{G})$.

arXiv:cond-mat/0702178Physical Review AJul 30, 200769 citations

Ultracold atoms in strong synthetic magnetic fields

Wolfgang Ketterle

Bulletin of the American Physical SocietyMar 2, 20150 citations

Evidence for Universal Four-Body States Tied to an Efimov Trimer

Francesca Ferlaino, Steven Knoop, Martin Berninger +4 more

We report on the measurement of four-body recombination rate coefficients in an atomic gas. Our results obtained with an ultracold sample of cesium atoms at negative scattering lengths show a resonant enhancement of losses and provide strong evidence for the existence of a pair of four-body states, which is strictly connected to Efimov trimers via universal relations. Our findings confirm recent theoretical predictions and demonstrate the enrichment of the Efimov scenario when a fourth particle is added to the generic three-body problem.We report on the measurement of four-body recombination rate coefficients in an atomic gas. Our results obtained with an ultracold sample of cesium atoms at negative scattering lengths show a resonant enhancement of losses and provide strong evidence for the existence of a pair of four-body states, which is strictly connected to Efimov trimers via universal relations. Our findings confirm recent theoretical predictions and demonstrate the enrichment of the Efimov scenario when a fourth particle is added to the generic three-body problem.

arXiv:0903.1276Physical Review LettersApr 6, 2009209 citations

Inducing Resonant Interactions in Ultracold Atoms with an Oscillating Magnetic Field

Dane Hudson Smith

Bulletin of the American Physical SocietyJun 9, 20150 citations

Magnetic field sweeps across a Feshbach resonance in ultracold gases

Masudul Haque, Henk T. C. Stoof

APSMar 1, 20040 citations

^{133}\mathrm{Cs}_{3}

resonance refers to a Borromean molecular state. We discuss how as yet unobserved, excited Efimov quantum states might be detected in ultracold gases of

^{85}\mathrm{Rb}

and of

^{133}\mathrm{Cs}

at magnetic field strengths in the vicinity of

0.08\phantom{\rule{0.3em}{0ex}}\mathrm{T}

(800\phantom{\rule{0.3em}{0ex}}\mathrm{G})