Toward a Rydberg constant measurement on circular atoms

A high-resolution spectroscopy experiment on the microwave transitions connecting circular states of lithium atoms was performed. A measurement of the Rydberg constant, directly in frequency units, with an uncertainty of less than 10/sup -10/ is reported. This experiment involves a continuous excitation of circular Rydberg atoms and requires typically a 1 ms interaction time with a 300-500 GHz microwave field. To obtain such an interaction time, laser deceleration of a thermal atomic beam and an extended microwave cavity is used.<
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