Metastable decay via quantum activation Mark Dykman, Professor of Physics, Michigan State University

Standard mechanisms of metastable decay are tunneling and thermal activation. We show that periodically modulated systems may display a different decay mechanism, quantum activation. Here, decay occurs via diffusion over a quasi-energy barrier. The diffusion is induced by quantum fluctuations. We study quantum activation for nonlinear oscillators and show that the decay rate displays unexpected features. It exhibits scaling behavior near critical parameter values where metastable vibrational states disappear. The results impose limitations on the characteristics of bifurcation amplifiers used in quantum measurements.