“…Still, the intrinsic experimental difficulties associated both with the measurements and the interpretation of the results have, so far, prevented an elucidation of the problem and, in fact, contradictory results persist, with some experiments obtaining a finite non-zero result [3,6] and others compatible with instantaneous tunneling [4]. It should be noticed that the similarity between Schrödinger and Helmholtz equations allows for analogies between quantum tunneling of massive particles and photons [7], and a noninstantaneous tunneling time is supported by this analogy and experiments measuring photonic tunneling times [8], as well as by many theoretical calculations based on both the Schrödinger (for reviews see, e.g., [1,2]) and the Dirac equations (e.g., [9][10][11][12][13][14][15][16]).…”