Comment on “Equivalence between SWH phase operator and Ban's phase operator revealed by virtue of the | η> representation” by Hong-yi Fan and Hui Zou
Fan and Zou [Phys. Lett. A 255 (1999) 7; 258 (1999) 74] prove and disprove the `identity' between the phase operator of Shapiro, Wagner and Hradil and that of Ban. The `nonequivalence' would be misleading by results of Hradil [Phys. Rev. A 47 (1993) 2376] and Ban [Phys. Rev. A 50 (1994) 2785].