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Complementary Metal Oxide Semiconductor (CMOS) annealing is a technology that was invented by Hitachi to artificially reproduce the behavior of the Ising model along a CMOS circuit. The new semiconductor computer (CMOS annealing machine) that utilizes this technology can efficiently find practical solutions to combinatorial optimization problems at below room temperature.

CMOS annealing is comprised of two processes. The first is reproducing the interactions between spins in the Ising model, decreasing the amount of energy in the Ising model. The second is injecting noise into the circuit that is reproducing the spins, intentionally disrupting the spins' states. With only the first process, the entire process becomes fixed, creating the risk that the process becomes fixed on a local solution (a section where energy expenditure is not at a minimum). Therefore, the second process avoids fixation on local solutions, seeking practical solutions (the section with the most minimal energy expenditure).

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