Photonic time-crystals (Conference Presentation)

Photonic Time Crystals (PTCs) are dielectric media whose refractive index is modulated periodically in time at time scales of an optical cycle. These systems conserve momentum but not energy, and are characterized by momentum bands and bandgaps, where the amplitudes of their eigenmodes can increase (or decrease) exponentially. But more interesting than all the rest - I will discuss the classical and quantum features of light emission in PTCs from various radiation sources, such as free electrons, classical dipoles, quantum fluctuations, and the emission by atoms. The latter opens new avenues for making widely tunable lasers that extract energy from the temporal modulation of the medium.