Quantum Hopfield Network Using Single-Electron Circuits—A Novel Hopfield Network Free from the Local-Minimum Difficulty

The concept of the quantum Hopfield network is proposed with examples of its network construction, which uses single-electron circuits. In this network, two or more threshold elements can change their outputs simultaneously in a form of coherent combination. This can be put into physical form by utilizing the co-tunneling phenomenon found in single-electron circuits. In the quantum Hopfield network, a state transition with a large Hamming distance can occur and therefore the local-minimum difficulty disappears; in consequence the global-minimum energy state can always be achieved. Use of this property made possible the development of novel computation devices that solve combinatorial problems without hindrance from the local-minimum difficulty.