A method implemented by an optical circuit, including beam splitter, phase shifters and cross-phase modulators, for solving Ising-model using quantum annealing discretizes a continuous time-dependent Hamiltonian function over a time period T, into a plurality of smaller portions; implements each of said smaller portions with a non-linear optical medium, and iterates over said smaller portions to output a solution of the Ising Hamiltonian problem, using the optical components.