  Multistability cannot be derived from any theoretical model that is based on
a monostable master equation. On the other hand, multistability is
experimentally-observed in a variety of quantum systems. A master equation
having a nonlinear term that gives rise to disentanglement has been recently
proposed . The dynamics governed by this master equation is explored for a
quantum system made of coupled spins. It is found that the added nonlinear term
can give rise to multistability. The spins' response to an externally applied
magnetic field is evaluated, and both a phase transition and a dynamical
instability are found. These findings, which originate from
disentanglement-induced multistability, indirectly support the hypothesis that
spontaneous disentanglement occurs in quantum systems.
