München 2004 – wissenschaftliches Programm
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Q: Quantenoptik und Photonik
Q 48: Laserspektroskopie und Pr
äsizionsmessungen
Q 48.4: Vortrag
Freitag, 26. März 2004, 11:45–12:00, HS 221
Preparation of an Optical Frequency Standard for an Uncertainty Level of 10−16 — •Guido Wilpers, Christopher W. Oates, and Leo Hollberg — National Institute of Standards and Technology, 325 Broadway, Boulder, Co. 80305, USA
We present a method to minimize the residual Doppler effect, which we can use to reduce its relative uncertainty contribution by two orders of magnitude to below 10−16 in our neutral atom calcium optical frequency standard. The approach uses atom interferometry to isolate and quantify the various laser beam parameters that contribute to the residual Doppler effect. We enhance the sensitivity by launching the ensemble of microkelvin neutral atoms. We discuss the application of this method to the clock transition of 40Ca at 657 nm (with its extreme insensitivity to external fields) to realize a frequency standard with a relative uncertainty at the 10−16 level. We present recent absolute frequency measurements of the Calcium clock transition. We discuss the implications of these results (in combination with measurements of the mercury ion standard) for laboratory tests of drifts in fundamental constants.