Selected elevation in quantum tunnelling

The tunnelling through an opaque barrier with a strong oscillating component is investigated. It is shown that in the non-weak perturbations regime (in contrast to the weak one), higher perturbations rate do not necessarily improve the activation. In fact, in this regime two rival factors play a role, and, as a consequence, this tunnelling system behaves like a sensitive frequency-shifter device: for most incident particles' energies activation occurs and the particles are energetically elevated, while for specific energies activation is depressed and the transmission is very low. This effect is unique to the strong perturbation regime, and it is totally absent in the weak-perturbation case. Moreover, it cannot be deduced even in the adiabatic regime. It is conjectured that this mechanism can be used as a frequency-dependent transistor, in which the device's transmission is governed by the external field frequency.