Lamb shifts, calculated observed

A small part of the infrared light was frequency doubled in a KNbC>3 crystal to 486 nm and combined with the blue light of the dye laser that excites the IS —2S transition. A fast photodiode is used to observe the frequency difference v(2S — AS/AD) — 1/4 v(lS — 2S). Fitting the 2S —4S and 2S — AD line profiles with a theoretical model calculated by Garreau et al. [17,18,19] and correcting for some systematic effects, the ground state Lamb shift could be determined with an accuracy of 1.3 parts in 105, one order of magnitude more precise than in previous measurements [21,22]. 

In all experiments the velocity was measured by observing the decay of the 2p atoms produced from the 2s atoms under the action of a nonadiabatic field. To determine the velocity from the experimentally obtained decay length 0 = vr, we must know t, i.e. the lifetime of the 2p state. The value of t was calculated the error was estimated to be of the order of 1 ppm, which is acceptable for the determination of the Lamb shift with approximately the same accuracy. 

Power of the renormalization procedure is in the treatment of QED as a fundamental constraint, not as a theory. We can calculate a long-range Coulomb-like interaction (which determines an observable value of the electric charge), we can study electron s kinetic (or complete) energy (which determines an observable value of the electron s mass) and we can measure a number of other properties such as the anomalous magnetic moment of an electron and the Lamb shift in the hydrogen atom. The constraint means that they are correlated and we can calculate the correlation. Learning some of these values from experiment, we can predict the others. 

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