Fig. 4

The experimental results of the 2D Ising machine. a The spin evolution and Ising energy as a function of the number of roundtrips at G_s = 1.01. b The Ising energy and the mean amplitude of the spins as functions of the number of roundtrips. c Snapshots of the spin evolution at some specific roundtrips (30, 400, 1200, 3000) at different values of G_s = {1.01, 1.05, 1.1}. At the small gains, the domain walls were smooth and small domains evaporated or merged into larger ones, ending up with a whole. At large gains, the domain walls were sharp at the beginning. As the number of roundtrips increased, the machine was trapped in local energy minima associated with parallel domain walls. The Ising machine reached the ground state in the first two cases and froze out in the last cases. d The success rate of cases as a function of the number of roundtrips at which the given percentage of the ground state energy was reached at different small-signal gains. e The superposition of domain walls at different numbers of roundtrips. The domain drift was removed through data processing for a better vision. The evaporation and shrinkage of the domain walls show the dynamics of the machine. The change in color of the contour lines from yellow to purple indicates an increase in the number of round trips