Quantum freeze of fidelity decay for chaotic dynamics
  We show that the mechanism of quantum freeze of fidelity decay for perturbations with zero time-average, recently discovered for a specific case of integrable dynamics [New J. Phys. 5 (2003) 109], can be generalized to arbitrary quantum dynamics. We work out explicitly the case of chaotic classical counterpart, for which we find semi-classical expressions for the value and the range of the plateau of fidelity. After the plateau ends, we find explicit expressions for the asymptotic decay, which can be exponential or Gaussian depending on the ratio of the Heisenberg time to the decay time. Arbitrary initial states can be considered, e.g. we discuss coherent states and random states. 
Tomaz Prosen and Marko Znidaric