Coherent control of atoms in the extreme ultraviolet and attosecond regime by synchrotron radiation

Control of interference between wave packets is one of the basic concepts in coherent control that enables quantum manipulation of populations and reaction pathways in matter. We have recently shown a new method to achieve coherent control in the extreme ultraviolet and attosecond regime using synchrotron radiation. This method is based on the use of longitudinal coherence of light wave packets that are naturally included in the undulator radiation. For quantum manipulation of atomic systems, wave packet interference is precisely controlled by tuning the time delay between the light wave packets. Here we show that the quantum phase controlled by the time delay can be monitored as an initial phase of the quantum beat oscillation in fluorescence decay.