Photon position operator with commuting components

A photon position operator with commuting components is constructed, and it is proved that it equals the Pryce operator plus a term that compensates f or the adiabatic phase. Its eigenkets are transverse and longitudinal vecto rs. and thus states can be selected that have definite polarization or heli city. For angular momentum and boost operators defined in the usual way, al l of the commutation relations of the Poincare group are satisfied. This ne w position operator is unitarily equivalent to the Newton-Wigner-Pryce posi tion operator for massive particles. [S1050-2947(99)02902-9].