Enhancement of activated decay of metastable states by resonant pumping

Publisher Website
Google Scholar
Abstract
We consider the effect of a high-frequency pumping E cosωt on the escape rate of a classical under-damped Brownian particle out of a deep potential well. The pumping frequency ω is assumed to be close to the frequency ω(0) of small oscillations. The energy dependence of the oscillation frequency ω(E) is also assumed to be weak on the scale of thermal energy, ωE′(0)T∼ω(0)T/U0≪ω(0) [ωE′(0) is the derivative of ω(E) at E=0, U0 is the barrier height, U0≫T]. The quadratic (in E) contribution to the decay rate is calculated exactly as a function of two reduced parameters, the anharmonicity of the potential ν≡ωE′(0)T/γ and the resonance detuning δ≡[ω-ω(0)]/γ, where γ is the friction coefficient. It is shown that the effect of the pumping increases with diminishing |ν| and at small ν is proportional to ν-1. In this regime dependence on δ is stepwise: the pumping contribution is large for νδ>0 and small for νδ