Quantum signature of the classical chaos in the field-induced barrier crossing in a quartic potential

The quantum domain behaviour of a classical double-well oscillator which ex hibits chaos in the presence of an external monochromatic field has been st udied using Bohmian mechanics. The classical Kolmogorov-Arnol'd-Moser (KAM) tori break down in the presence of an external perturbation for which the corresponding quantal phase portrait exhibits regular islands owing to the quantum suppression of the classical chaos. It has also been observed that the classical chaos generally enhances the quantum fluctuations.