Quantum-mechanical P function for photons

In this paper, we have introduced a process that has furnished a novel weight function. This function relates to the Glauber-Sudarshan P distribution function for chaotic fields through a nonlinear relation. It is found that the new function is available to define the P representation for the squeezed states that are pure quantum-mechanical states of photons. A nondiagonal form for the density operator for a single-mode squeezed vacuum is exhibited. This form leads to interesting new concepts concerning the structure of the density matrix for photons.