Quantum annealing by ferromagnetic interaction with the mean-field scheme

Quantum annealing is a novel method for combinatorial optimization problems. In this paper, we discuss the appropriate choice of quantum fluctuations in quantum annealing. The existence of room of choices of quantum fluctuations is an advantage of quantum annealing over simulated annealing. We consider the ferromagnetic interaction as a source of quantum fluctuations. Using the mean-field annealing scheme, we show that quantum annealing by ferromagnetic interaction is more efficient than the conventional quantum annealing and simulated annealing in the ground state search of the random-field Ising model.