A unified view to Cologne and Florence experiments on superluminal photon propagation

We show that two of the first performed experiments on superluminal photon propagation, namely,,the 1992 Cologne experiment on the tunneling of evanescent waves in an undersized waveguide, and the 1993 Florence experiment on the microwave propagation in vacuum between two horn antennas, do admit a common interpretation. Precisely, both experimental devices behave as a high-pass filter. We get this result by two different methods, one based on the Friis law (which yields the efficiency of a transmitting device), and the other on the deformation of the Minkowski space-time. This allows us to set intriguing connections between these two (a priori different) classes of experiments. In particular, in either case the superluminal propagation can be described as a tunneling and is related to evanescent waves. (C) 2002 Elsevier Science B.V. All rights reserved.