Hi, In quantum physics, solution of Shrodinger equation live in a Hilbert space which is a vector space. The state superposition is obtained by mixing solution of the équation which is LINEAR so a linear combination of solution is a solution. Now i have a non-linear equation of a scalar field named Q. So a linear combination of solution of Q is not a solution. To obtain a state superposition, i define a probability density P over the space of all scalar field which is a functionnal space. Is it a good way ? did you know similar aproach ? Because, now at the oposite of Shrodinger equation, the time evolution is a modification of density P over time. I have strong difficulties to write the equation which control P over time because it need to derivate a scalar field defined over a function space. Thanks for your answer.