Konwersatorium im. Leopolda Infelda

Uncertainty relation for photons that overcomes the difficulties caused bythe nonexistence of the photon position operator is derived in quantumelectrodynamics. The photon energy density plays the role of theprobability density in configuration space. It is shown that the measureof the spatial extension based on the energy distribution in spacecombined with a measure of the spread in the photon momentum leads to an inequality that is a natural counterpart of the standard Heisenbergrelation. Unexpectedly, the equation satisfied by the photon wave functionin momentum space which saturates the uncertainty relations has the form of the Schroedinger equation in coordinate space in the presence of electric and magnetic charges.