  A new technique is demonstrated for carrying out exact positive-P phase-space
simulations of the coherent Ising machine quantum computer. By suitable design
of the coupling matrix, general hard optimization problems can be solved. Here,
computational quantum simulations of a feedback type of photonic parametric
network are carried out, which is the implementation of the coherent Ising
machine. Results for success rates are obtained using this scalable phase-space
algorithm for quantum simulations of quantum feedback devices.
