Comment on "A classical model for asymmetric sidebands in cavity optomechanical measurements"

We respond to a recent manuscript by Tsang [arXiv:1306.2699], on whether the measurement presented in Safavi-Naeini et al. [Phys. Rev. Lett. 108, 033602 (2012)] can be explained "without reference to quantum mechanics". We show that the fully classical analysis provided by Tsang, and previously by Safavi-Naeini et al. [New J. Phys. 15, 035007 (2013)], has been ruled out by our published data. In addition, we discuss the role of the mathematical formulation used on the interpretation of the asymmetry effect, as has previously been considered by Khalili et al. [Phys. Rev. A 86, 033840 (2012)].