Time-Domain Bound States in the Continuum

We present the concept of time-domain bound states in continuum. We show that a rapid judiciously designed temporal modulation of the refractive index in a spatially homogenous medium gives rise to a bound state in time, embedded in a continuum of wave numbers. Mathematically, these bound states in the continuum are closed form solutions of the Maxwell equations in time and one-dimensional space. Our results show the potential to extend known wave phenomena in space to the temporal domain, providing new avenues for light-matter interactions in time-varying media.