  We propose a simple model for an atomic switch-based decision maker (ASDM),
and show that, as long as its total volume of precipitated Ag atoms is
conserved when coupled with suitable operations, an atomic switch system
provides a sophisticated "decision-making" capability that is known to be one
of the most important intellectual abilities in human beings. We considered the
multi-armed bandit problem (MAB); the problem of finding, as accurately and
quickly as possible, the most profitable option from a set of options that
gives stochastic rewards. These decisions are made as dictated by each volume
of precipitated Ag atoms, which is moved in a manner similar to the
fluctuations of a rigid body in a tug-of-war game. The "tug-of-war (TOW)
dynamics" of the ASDM exhibits higher efficiency than conventional MAB solvers.
We show analytical calculations that validate the statistical reasons for the
ASDM dynamics to produce such high performance, despite its simplicity. These
results imply that various physical systems, in which some conservation law
holds, can be used to implement efficient "decision-making objects." Efficient
MAB solvers are useful for many practical applications, because MAB abstracts a
variety of decision-making problems in real- world situations where an
efficient trial-and-error is required. The proposed scheme will introduce a new
physics-based analog computing paradigm, which will include such things as
"intelligent nano devices" and "intelligent information networks" based on
self-detection and self-judgment.
