Fhm. Faisal et U. Schwengelbeck, UNIFIED THEORY OF LYAPUNOV EXPONENTS AND A POSITIVE EXAMPLE OF DETERMINISTIC QUANTUM CHAOS, Physics letters. A, 207(1-2), 1995, pp. 31-36
A unified theory of quantum Lyapunov exponents, based on the Hamilton-
Jacobi formulation of quantum mechanics, is applied to Weigert's quant
um cat map. It is shown to provide a definite positive example of dete
rministic quantum chaos in terms of extreme sensitivity on initial con
ditions and a positive definite Lyapunov exponent.