(b) There will be heating limiting the available measurement time.
(3) The authors claim there should be no backaction of the field on the oscillation frequencies. Also the BEC will lead to an effective change of the cavity length and lattice constant, which should renormalize the wavelength and thus om_recoil. This is somehow in contradiction with the eigenfrequency calculations (see Fig.4) in Horak, P.,Physical Review A, 61(3), 033609, 2000.