Wigner distribution function formalism for superconductors and   collisionless dynamics of the superconducting order parameter
  A technique to study collisionless dynamics of a homogeneous superconducting system is developed, which is based on Riccati parametrization of Wigner distribution function. The quantum evolution of the superconductiung order parameter, initially deviated from the equilibrium value, is calculated using this technique. The effect of a time-dependent BCS paring interaction on the dynamics of the order parameter is also studied. 
M.H.S. Amin, E.V. Bezuglyi, A.S. Kijko, A.N. Omelyanchouk