Spatial vibrations suppressing resonant tunneling

Gilad Zangwill and Er'el Granot

The dynamics of resonant tunneling via a spatially oscillating narrow well is investigated. The well generates a quasiresonance state, which can trap the incoming particles. Four spectral regimes are found: (1) the adiabatic regime, when the vibrations’ frequency is lower than the spectral width of the resonance. In this regime, the mean current is independent of the vibration's frequency, and the current decreases as a function of the vibration's amplitude. (2) When the frequency of the vibration is higher than the spectral width of the resonance, the particle is partially trapped to the moving well and the dependence of the current on the vibrations’ amplitude is more moderate. (3) However, and this is the main result of this paper, beyond a certain frequency the kinetic energy of the trapped particle exceeds the spectral width of the resonance, in which case particles cannot be trapped in the moving well and the current is abruptly suppressed. (4) When the energy quanta of the vibrations are higher than the energy gap between the resonance energy and the barrier's potential height, a single phonon can be absorbed by the particle only when the final energy agrees with the resonances of the barrier, in which case current suppression is selective and occurs only for specifics frequencies. The model is solved exactly numerically, and analytical approximations are presented for the different regimes. The analytical solutions show high agreement with the numerical ones. This effect can be implemented in extremely sensitive accelerometers. Moreover, it may explain the odor receptor's sensitivity to molecular vibrations.

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