Lecturer: Dr. Ido Kaminer Affiliation: Israel Institute of Technology - Technion Abstract: When a charged particle travels faster than the phase velocity of light in a medium, it produces Čerenkov radiation. We show that the Čerenkov Effect contains new phenomena arising from the quantum nature of a charged particle. Specifically, with proper design of particle wavepacket, we predict the traditional Čerenkov radiation angle splits into two distinctive cones of photonic shockwaves. One of the shockwaves can move along a backward cone, otherwise considered impossible for Čerenkov radiation in ordinary matter. More importantly, and more generally, the spectral response reveals an upper frequency cutoff at which the photon emission rate is diverging – manifesting a new resonant light-matter interaction. The origins of the major deviations from the known understanding of the Čerenkov effect are the nonlinear nature of the interaction, and its spatial extent that exceeds the wavelength of the emitted radiation. Importantly, our findings are observable for electron beams with realistic parameters, offering new applications including coherent x- ray sources and open a new realm for Čerenkov detectors. ‏האירוע הזה כולל שיחת וידאו ב-Google Hangouts. הצטרף: https://hangouts.google.com/hangouts/_/mail.huji.ac.il/condensed?hceid=b...