Statistical Behavior in Deterministic Quantum Systems with Few Degrees of Freedom

Numerical studies of the dynamics of finite quantum spin chains are presented which show that quantum systems with few degrees of freedom ($N=7\mathrm{}$) can be described by equilibrium statistical mechanics. The success of the statistical description is seen to depend on the interplay between the initial state, the observable, and the Hamiltonian. This work clarifies the impact of integrability and conservation laws on statistical behavior. The relation to quantum chaos is also discussed.