Date: June 15, 1992
Creator: Bonci, Luca; Roncaglia, Roberto; West, Bruce J. & Grigolini, Paolo
Description: Article on semiclassical chaos, the uncertainty principle, and quantum dissipation. Abstract: Using the Wigner method, it is shown that a classical-like equation of motion for a quasiprobability distribution ρᴡ can be built up, ∂ρᴡ/∂t=(Lcl+LQGD)ρᴡ, which is rigorously equivalent to the quantum von Neumann-Liouville equation. The operator Lcl is equivalent to integrating classical trajectories, which are then averaged over an initial distribution, broadened so as to fulfill the requirements of the quantum uncertainty principle. It is shown that this operator produces semiclassical chaos and is responsible for quantum irreversibility and the fast growth of quantum uncertainty. Carrying out explicit calculations for a spin-boson Hamiltonian, the joint action of Lcl and LQGD is illustrated. It is shown that the latter operator LQGD (where QGD stands for quantum generating diffusion), makes the 1/2-spin system "remember" its quantum nature, and competes with the irreversibility induced by the former operator. Some ambiguous aspects of "irreversibility" and "growth of quantum fluctuations" as indicators of semiclassical chaos are discussed.
Contributing Partner: UNT College of Arts and Sciences