There is a conceptual mistake in the extraction of the Rabi splitting from the simulated data shown in Fig. 2. In fact, the Rabi splitting should be evaluated from the dispersion as a function of wave vector, which, for our structure, yields a corrected value of 5.4 meV instead of 6 meV. Therefore, in the abstract the corrected text should be: “the exciton photon coupling is more than 40% larger as compared to….” The text at the bottom of the first column in pp. 121118–2 should read as “the predicted resonance splitting is about 5.4 meV. This value is more than 40% larger….” In the caption of Fig. 2 we correct as “(b) attenuated total reflectance (ATR) spectrum for the angle of incidence at which the exciton and the photon resonances have the same energy, i.e., dashed line in (a).”