  We discuss the effect of slow phase relaxation and the spin off-diagonal
$S$-matrix correlations on the cross section energy oscillations and the time
evolution of the highly excited intermediate systems formed in complex
collisions. Such deformed intermediate complexes with strongly overlapping
resonances can be formed in heavy ion collisions, bimolecular chemical
reactions and atomic cluster collisions. The effects of quasiperiodic energy
dependence of the cross sections, coherent rotation of the hyperdeformed
$\simeq (3:1)$ intermediate complex, Schr\"odinger cat states and
quantum-classical transition are studied for $^{24}$Mg+$^{28}$Si heavy ion
scattering.
