Bound-state interferometry using incoherent light

Abstract

Rydberg states in sodium are excited using two identical broadband, dye laser pulses. Each 8 ns pulse has a bandwidth of approximately 45 cm-1, and Rydberg states with several different principal quantum numbers are simultaneously excited. The number of Rydberg atoms created by each pulse pair is detected as a function of the delay between the two pulses. Strong modulations in the population in each Rydberg level and in the total Rydberg signal are observed. The oscillations are identical to those which would be expected if two transform-limited, 300 fs laser pulses had been used. We show explicitly, in the limit of weak pulses, that these 'bound-state interferograms' acquired using the time-domain, Ramsey separated-oscillatory fields method are only dependent on the excitation cross section and pulse frequency spectrum. Therefore, weak-field interferograms do not in themselves give information on the spatial-distribution of the electron wavefunction. In addition, the benefits of using strong or weak pulses for bound-state interferometry are discussed.