Multibarrier tunneling.

We study the tunneling through an arbitrary number of finite rectangular opaque barriers and generalize earlier results by showing that the total tunneling phase time depends neither on the barrier thickness nor on the interbarrier separation. We also predict peculiar features of the system considered, namely the independence of the transit time (for nonresonant tunneling) and the resonant frequency on the number of barriers crossed, which can be directly tested in photonic experiments. A thorough analysis of the role played by interbarrier multiple reflections and a physical interpretation of the results obtained is reported, showing that multibarrier tunneling is a highly nonlocal phenomenon.