Quantum chaos and complexity in nuclei

A mesoscopic system with strong interaction between constituents, the atomic nucleus is a good candidate for studying the manifestations of quantum chaos. Recent experimental and theoretical developments give clear evidence of the dominant role chaotic dynamics plays not only in local level statistics, but also in the damping of collective motion, isospin and parity nonconservation, thermalization, and decay into continuum. In this review, those and other phenomena are discussed from the general viewpoint of quantum chaos and complexity. The complexity of eigenstates measured by information entropy in the mean-field basis is more informative than the standard signatures of chaos in the level statistics. It evolves regularly as a function of excitation energy and provides an alternative temperature scale. This sheds new light on the problems of foundations of statistical mechanics and quantum decoherence.