Certain integrable system on a space associated with a quantum search   algorithm
  On thinking of a Grover-type quantum search algorithm for an ordered tuple of multi-qubit states, a gradient system associated with the negative von-Neumann entropy is studied on the space of regular relative-configurations of multi-qubit states (SR${}^2$CMQ). The SR${}^2$CMQ emerges, through a geometric procedure, from the space of ordered tuples of multi-qubit states for the quantum search. The aim of this paper is to give a brief report on the integrability of the gradient dynamical system together with quantum information geometry of the underlying space, SR${}^2$CMQ, of that system. 
Yoshio Uwano, Hideitsu Hino and Yasue Ishiwatari