Comment on: open-quotes Interference effects between independent gamma raysclose quotes

In a recent letter, E. Ikonen proposed a Hanbury Brown and Twiss (HBT) intensity interferometry experiment to demonstrate interference effects between independent gamma rays. Ikonen suggests that in order to obtain a measurable correlation signal with gamma or x-radiation, it would be necessary to use a highly monochromatic beam such as that produced by a monochromator based on the Mossbauer effect, operating on a high brilliance beamline at a synchrotron storage ring. In this comment, the authors point out that, although this is a possible approach, it is unnecessary to utilize the extremely narrow bandwidth afforded by nuclear resonant monochromatization to demonstrate the HBT effect with x-rays. Furthermore, they do not agree that the proposed experiment would provide evidence of interference between independent quanta in the x-ray region, or that the results of such an experiment depend on quantum phenomena which are fundamentally different than those which apply to conventional (amplitude) interferometry