Quantum-classical correspondence in localization of eigenstates for a system having mixed-type classical dynamics.

We have examined the localization properties of quantum eigenstates for a system having mixed-type classical dynamics. Emphasis is given to the structure of eigenfunctions and the local spectral density of states. The nature of strongly localized eigenstates can be explained by considering the corresponding classical motion on the Kolmogorov-Arnold-Moser tori. The weak localization of nearly delocalized eigenstates is not a quantum effect as is dynamical localization but a consequence of classical dynamics.