2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/93601The different time-dependent distances of two arbitrarily close quantum or classical-statistical states to a third fixed state are shown to imply an experimentally relevant notion of state sensitivity to initial conditions. A quantitative classification scheme of quantum states by their sensitivity and instability in state space is given that reduces to the one performed by classical-mechanical Lyapunov exponents in the classical limit1 .tex file and 2 .ps figures. Physical Review A (to appear 1 May)Quantum Physicstext