  We present a generalized information-theoretic measure of synchronization in
quantum systems. This measure is applicable to dynamics of anharmonic
oscillators, few-level atoms, and coupled oscillator networks. Furthermore, the
new measure allows us to discuss synchronization of disparate physical systems
such as coupled hybrid quantum systems and coupled systems undergoing mutual
synchronization that are also driven locally. In many cases of interest, we
find a closed-form expression for the proposed measure.
