Time-delayed interferometry with nuclear resonant scattering

Experimental results of "time-delayed interferometry" with nuclear resonanc es at KEK are reported. Mossbauer nuclei were used as a cavity for X-rays i n these experiments. Various interference effects were observed on a macros copic scale with the "perfect crystal" interferometer. The property of cohe rence and the combined system showed some characteristics of collective nuc lear excitations, e.g., absorption of photons without the reduction of the detection probability, the phase information transfer, and spontaneous emis sion with phase relation. Interferometry with a large optical path length, i.e., 4.2 mm, was accomplished with a wave-front division type X-ray interf erometer. An interference experiment with a vibrating resonant scatterer ex hibited quantum beat oscillations in the time domain. Interferograms with s amples of different thicknesses revealed a remarkable phase shift of pi in the time evolution, which is induced by the dispersion effect at the nuclea r resonance. A future perspective of time-delayed interferometry is also pr esented, e.g., for temporal phenomena in nuclear resonant scattering. Time- delayed interferometry has established a new field of X-ray optics, which c an be of help for fundamental, nuclear, and solid state physics.