Origin of chaos near critical points of quantum flow

The general theory of motion in the vicinity of a moving quantum nodal point (vortex) is studied in the framework of the de Broglie - Bohm trajectory method of quantum mechanics. Using an adiabatic approximation, we find that near any nodal point of an arbitrary wavefunction $\psi$ there is an unstable point (called X-point) in a frame of reference moving with the nodal point. We find general formulae for the nodal point - X-point complex as well as necessary and sufficient conditions of validity of the adiabatic approximation. Chaos emerges from the consecutive scattering events of the orbits with nodal point - X-point complexes. A theoretical model is constructed yielding the local value of the Lyapunov characteristic number in a scattering event, which scales as an inverse power of the speed of the nodal point in the rest frame, or proportionally to the size of the nodal point X- point complex. The results of detailed numerical experiments with different wavefunctions possessing multiple moving nodal points are reported. The statistics of the Lyapunov characteristic numbers of the orbits are found and compared to the number of encounter events of each orbit with the nodal point X-point complexes. Various phenomena appearing at first as counter-intuitive find a straightforward explanation.