Quantum and classical ergodicity of spinning particles

We give a formulation of quantum ergodicity for Pauli Hamiltonians. with ar bitrary spin in terms of a Wigner-Weyl calculus. The corresponding classica l phase space is the direct product of the phase space of the translational degrees of freedom and the two-sphere. On this product space we introduce a combination of the translational motion and classical spin precession. We prove quantum ergodicity under the condition that this product flow is erg odic. (C) 2001 Academic Press.