  Yangian $Y(sl(2))$ is realized in the bi-spin system coupled with a
time-dependent external magnetic field. It is shown that $Y(sl(2))$ generators
can describe the transitions between the ``spin triplet'' and the ``spin
singlet'' that evolve with time. Furthermore, new transition operators between
the states with Berry phase factor and those between the states of Nuclear
Magnetic Resonance (NMR) are presented.

Disordered Systems and Neural Networks