•The simple explanation by Einstein in terms of absorption of single
quanta of light explained the features of the phenomenon and helped explain
the characteristic frequency. Einstein's explanation of the photoelectric
effect won him the Nobel Prize of 1921.
•The concept of the photon in the quantum theory of a radiation field has
been built on the number (Fock) state |n> The number states are eigenstates of the field Hamiltonian of the
harmonic oscillator and exhibit no phase information.