  In this paper, we review some features of quantum annealing and related
topics from viewpoints of statistical physics, condensed matter physics, and
computational physics. We can obtain a better solution of optimization problems
in many cases by using the quantum annealing. Actually the efficiency of the
quantum annealing has been demonstrated for problems based on statistical
physics. Then the quantum annealing has been expected to be an efficient and
generic solver of optimization problems. Since many implementation methods of
the quantum annealing have been developed and will be proposed in the future,
theoretical frameworks of wide area of science and experimental technologies
will be evolved through studies of the quantum annealing.
