Short time quantum phase space dynamics at a 1:2 Fermi resonance Original Research Article

The short time dynamics of a wavepacket initiated on the unstable classical periodic orbit of a 1:2 Fermi resonance are investigated in cases that give rise to regular and near chaotic classical motion. In both cases the spectral decomposition reveals an imprint of the periodic orbit frequency but there is a broader additional fine structure in the irregular case. A Husimi phase space representation of the wavepacket shows that two separate time components in the autocorrelation function are associated with motion on two distinct branches of the separatrix attached to the unstable orbit. The wavepacket in the irregular case is also found to be controlled by the now broken separatrix or homoclinic tangle. The autocorrelation function again shows recurrences indicative of a residual compact component to the wavepacket.