Comment on the paper: Quantum backaction of optical observations on   Bose-Einstein condensates by U. Leonhardt, T. Kiss, and P. Piwnicki, Eur.   Phys. J. D7, 413 (1999)
  A recent paper, Quantum backaction of optical observations on Bose-Einstein condensates by U. Leonhardt, T. Kiss, and P. Piwnicki, Eur. Phys. J. D7, 413 (1999), emphasized that the limit of dispersive imaging of Bose-Einstein condensates with off-resonant light is not residual absorption, but a different form of quantum backaction of the probe light. This note points out that these conclusions are incorrect, and that Rayleigh scattering is the dominant quantum backaction of dispersive imaging. 
Wolfgang Ketterle