  Various charge pairings in strongly correlated electron systems are
interpreted as quantum entanglement of a composite system. Particles in the
intermediate phase have a tendency to form the coherent superposition state of
the localized state and the itinerant state, which induces the entanglement of
both particles in the bipartite subsystems for increasing the entropy of the
system. The correction to the entropic Coulomb force becomes an immediate cause
of charge pairing.
