Selected elevation in quantum tunnelling

Abstract

The tunneling through an opaque barrier with a strong oscillating component is investigated. It is shown, that in the strong perturbations regime (in contrast to the weak one), higher perturbations rate does not necessarily improve the activation. In fact, in this regime two rival factors play a role, and as a consequence, this tunneling 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.

The Tunnelling Current through Oscillating Resonance and the Sisyphus Effect

“…These results suggest that activation is not an optimal method to increase the mean current; however, they do show that the current can easily be controlled by changes in the frequency and therefore may be used in frequency effect devices [20,41].…”

“…Therefore, the ratio between the average current and the stationary one depends on a single complex parameter 0 (20). The maximum average current (⟨ ⟩ max ) is reached, within this adiabatic approximation, when the lower value of the resonance eigenbound state is equal to the incoming particle's energy, that is, for Ω = − ( 0 + Δ ) 2 /4, or Δ = 2 − 0 , for which case…”

“…As a consequence, the particle can be activated to much higher energies (close to the barrier's height) and penetrates through the well with much higher probability. This dynamic resonant tunnelling was investigated in a variety of fields: from the foundations of quantum mechanics [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] via nano-and microelectronics [14,[31][32][33] to biochemistry and biology [34][35][36][37][38][39][40].…”

“…This process was termed eigenstate assisted activation (EAA) and the elevator effect (EE) by Azbel [15,17]. However, recently, it has been shown that the eigenstate's presence can suppress the activation and reduce the transmission [20,30,41]. Despite the fact that an additional energy is introduced to the system via the potential oscillations, the net effect is current reduction; therefore, the Sisyphus effect (after the mythological hero) is a more adequate name for the effect.…”

“…In fact, when there is a destructive interference between the two time events, in which the well's eigenenergy crosses the incoming particles energy, the particle cannot dwell in the well and activation is suppressed. This effect occurs for specific energies, and in very narrow spectral bands, and therefore it was suggested that it can be used for a frequency effect transistor, where the current is controlled by the frequency of the gate [20,41].…”