  Photonic Time Crystals (PTCs) provide a completely new platform exhibiting
light wave amplification owing to periodically varying electromagnetic
properties. The need to control this amplification is becoming increasingly
important, especially with the emergence of meta surface based practical
realization of PTCs. The work introduces isolated temporal defect in PTCs to
establish a new degree of control over the amplification. We find that in
presence of the defect, the transmittance and reflectance become close to unity
for a specific value of momentum (k_d) within the bandgaps accompanied by a
significant impact on the amount of amplification. We show the impact of the
temporal defect on the exponential growth of intensity with PTC periods. The
effect primarily depends on the Floquet frequency of the PTC that becomes real
at k_d giving rise to four pulses instead of two as an outcome of gap
propagation. We further demonstrate that by manipulating the temporal and
dielectric properties of the defect, the defect state in momentum can be tuned
to serve the design interest for specialty applications.
