Non-Markovian autoresonant dynamics of tunneling from discrete to continuum modes.

We study the autoresonant dynamics of a discrete level coupled to a continuum, and show that passing adiabatically through a linear resonance, above a well-defined threshold, yields a transition to nonlinear phase locking and linear non-Markovian decay to the continuum. This process results in broadening of the population of the continuum modes beyond its natural linewidth. This concept can be employed to alter spontaneous emission, where driving an atom into phase locking with continuum modes will yield the emission of short pulses. [ABSTRACT FROM AUTHOR]