Superluminal tunneling through two successive barriers: Does QM predicts infinite group-velocities?

The phenomenon is analyzed of one-dimensional non-resonant tunneling through two or more successive (opaque) potential barriers, separated by intermediate free regions R, just by exploiting the relevant solutions to the Schroedinger equation. The total traversal time has been shown by us to be independent not only of the barrier widths (the so-called “Hartman effect”), but also of the R-widths: so that the effective group-velocity in the regions R, between two successive barriers, can be regarded as practically infinite. We can announce that such a prediction has been already theoretically confirmed and generalized (as well as interpreted in terms of “super-oscillations”) by Aharonov et al. Even more, a very recent experiment by Longhi et al. (at the Politecnico di Milano) has supported our predictions by considering two successive gratings in an optical fiber, that is, by having recourse to two “classical barriers” (which allow simulating the tunneling, due to the known formal identity between the Schroedinger and the Helmholtz equation).