Antibunched statistics of heralded photon states

Here we develop a theoretical formalism of heralded photon states in both pure coherent state generated by PDC and mixed Poissonian pair states from TPE. We demonstrate theoretically continuous second order correlation function g(²)(tau) for heralded states exhibiting antibunched statistics. Furthermore, being time entangled with the detected heralding state, the signal state bares the signature of the time-dependence of the heralding state reduction according to the Copenhagen interpretation. In usual photon detection it is impossible to retrieve the exact time dependence of the measurement processes due to the annihilation of the absorbed photon. Heralded state, however, provides a unique insight into the measurement and state collapse of the herald photon not described by the Schrodinger equation.