1. A method of factoring a product, the method comprising: setting an initial condition of a multiplication circuit, wherein: the multiplication circuit includes a plurality of quantum devices and a plurality of coupling devices between pairs of quantum devices; and the initial condition includes: a local bias value for at least one quantum device; a coupling value for at least one coupling device; and a binary value of the product to be factored; performing a backwards evolution of the multiplication circuit; and reading out a final state of at least one of the quantum devices, thereby determining a factor of the product.