Temporal profiles (IMAGE) National Institutes of Natural Sciences Caption Fig. 2. Top Panel shows fluorescence intensity from inner shell excited states of xenon atoms measured with changing time intervals of the wave packet pairs. Lower Panels show magnified views at positions a and b in top Panel. Fluctuations with a period of 63 attoseconds are observed due to the interference effect between the quantum states excited by the wave packet pairs. As the time interval between the two wave packets in a pair increases, the amplitude of the fluctuation decays due to electronic relaxation of the inner shell excited states. Credit NINS/IMS Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.