“…A tunable pulsed laser is the standard excitation source in the current quantum beat measurements (Bitto & Huber, 1990;Hack & Huber, 1991;Carter & Huber, 2000). In contrast, although synchrotron radiation of a continuous spectrum extending as far as the hard X-ray range can be a useful excitation source for quantum beat measurements, reports on quantum beat measurement using synchrotron radiation are limited only to Stark-split Rydberg states in Ar (Morioka et al, 2001;Aoto et al, 2005).…”