Chaotic systems in complex phase space
  This paper examines numerically the complex classical trajectories of the kicked rotor and the double pendulum. Both of these systems exhibit a transition to chaos, and this feature is studied in complex phase space. Additionally, it is shown that the short-time and long-time behaviors of these two PT-symmetric dynamical models in complex phase space exhibit strong qualitative similarities. 
Carl M. Bender, Joshua Feinberg, Daniel W. Hook, and David J. Weir