Quasi-coherent states for a photon in time varying dielectric media

► The quasi-coherent states of a photon are found in a time dependent medium. ► We show that the uncertainty in the electric field decreases. ► We show that the uncertainty in the magnetic field increases. ► We show that the product of uncertainties is always larger than the minimum value 1/4. ► Time dependent number states and their time evolution are also found.