We investigate the nonlinear dynamics of a mesoscopic driven Duffing
oscillator in a quantum regime. In terms of Wigner function, we identify the
nature of state near the bifurcation point, and analyze the transient process
which reveals two distinct stages of quenching and escape. The rate process in
the escape stage allows us to extract the transition rate, which displays
perfect scaling behavior with the driving distance to the bifurcation point. We
numerically determine the scaling exponent, compare it with existing result,
and propose open questions to be resolved.Comment: 4 pages, 4 figures; revised version accepted for publication in EP
