Tunneling time in fluctuating symmetric double wells: Suppression and enhancement of tunneling by spatial symmetry-preserving perturbations

摘要

We investigate how tunneling-time gets affected by spatial symmetry preserving fluctuations in the parameters determining the width, barrier height and well-depth of a symmetric double-well potential. Sinusoidal and rectified sinusoidal fluctuations of the well-parameters are shown to have contrasting effects. Significant enhancement of tunneling is noticed when the well-parameters fluctuate sinusoidally with frequency ω ≈ ω_0 while under rectified sinusoidal perturbation, quenching of tunneling takes place at a fluctuation frequency ω≈12ω0,ω0, being the frequency of the lowest transition allowed by the fluctuation induced spatial perturbation of even parity. Time-dependent Hellmann-Feynman theorem is invoked to analyze the energy changes induced by fluctuations. It turns out that the enhancement of tunneling in the sinusoidally fluctuating double well at frequency ω ≈ ω_0 is caused by transition to 1 ± levels under the barrier while in the rectified sinusoidal field at ω≈12ω0, a two-photon like process suppresses the tunneling by inducing barrier localization.