SIGNIFICANT EVENTS - SCIENCE EVENTS
07/25/03

Laurels Continue to Flow to Ketterle

Last November we reported that Wolfgang Ketterle of MIT had recently been elected to the European Academy of Sciences and to the Academy of Sciences of Heidelburg, and he had also been selected as a foreign associate of the National Academy of Sciences in the U.S., and was elected a fellow of the American Institute of Physics. Now he reports that he has also been awarded the Medal of Merit of the State of Baden-Wuertemberg. As well, he has received the Knight Commander's Cross (Badge and Star) of the Order of Merit of the Federal Republic of Germany.

So why should he be the beneficiary of so much recognition? We start this week to describe the continuing flow of new results that his group has produced recently. The June 13 issue of Science contains his group's article RF Spectroscopy of Ultracold Fermions (S. Gupta, Z. Hadzibabic, M.W. Zwierlein, C.A. Stan, K. Dieckmann, C.H. Schunck, E.G.M. van Kempen, B.J. Verhaar, and W. Ketterle, Science 300, 1723-1726 (2003)). The article describes probing a sample of ultra-cold fermions with RF signals to study the occupation of the energy levels available to the atoms. The researchers observed the expected absence of frequency shift for these cold fermions, suggesting these atoms may provide a higher-resolution clock signal than bosons can generate. By sweeping a magnetic field across the resonance value near 800 Gauss, they also saw the strong interactions and resulting frequency shifts generated by the Feshbach resonance in this system. But the shifts were anomalously small in the region where the resonance was expected to be largest.

Radio-frequency probe of atomic interactions

When this article appeared on the ScienceExpress web site, two follow-on commentaries related to it appeared. Adrian Cho of ScienceNOW (http://sciencenow.sciencemag.org/cgi/content/full/2003/509/1) declared the result an important step toward obtaining superfluidity in these fermions, in addition to the possible application to better clocks. In the Perspectives section of Science (13 June 2003, p. 1671), Massimo Inguscio noted that very small shifts were observed in the high-interaction region of the Feshbach resonance, and commented that new physics is occurring there, with the expectation that important developments will come soon.



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