1 S.. Blatt, A.D. Ludlow, G.K. Campbell, J.W. Thomsen, T.. Zelevinsky, M.M. Boyd, J.. Ye, X.. Baillard, M.. Fouché, R.. Le Targat, A.. Brusch, P.. Lemonde, M.. Takamoto, F.-L.. Hong, H.. Katori, and V.V. Flambaum, Physical Review Letters 100, (2008).