Quantum dynamics and dissipation effects in the resonant tunneling of molecular magnets

The quantum dynamics of nano-scale molecular magnets is studied from a viewpoint of adiabatic transition in a time dependent external field. The effect of noise is studied by the quantum Langevin equation and the quantum master equation, and how the pure quantum dynamics is disturbed by the noise is investigated. The origin of the quantum fluctuation is studied for Heisenberg antiferromagnets with half-odd-integer spins on a ring. Novel use of quantum dynamical effects is also discussed.