Berry's phase with quantized field driving: effects of inter-subsystem   coupling
  The effect of inter-subsystem couplings on the Berry phase of a composite system as well as that of its subsystem is investigated in this paper. We analyze two coupled spin-$\frac 1 2 $ particles with one driven by a quantized field as an example, the pure state geometric phase of the composite system as well as the mixed state geometric phase for the subsystem is calculated and discussed. 
L. C. Wang, H. T. Cui, and X.X. Yi