Further studies will be necessary to explore the validity of the HQM. We regard this article as an invitation to a discussion, which we start by the question how to interpret the effect of the power broadening induced by a plasmonic cavity. An incoming photon that probes the unexcited system already detects the modified permittivity. In that sense, it is already the vacuum ground state of the plasmonic cavity that alters the optical properties of the excitonic system. We could thus regard the effect as some kind of 'vacuum induced power broadening'. At first, such an interpretation seems rather counterintuitive, although other vacuum induced effects such as the Purcell effect 5 , spontaneous emission 22 , parametric fluorescence and vacuum Rabi splitting 23 are wellestablished. Vacuum fields have been proven to modify the properties of two-level quantum systems, and power broadening would represent another realization of such QED effects.