Conditions on systems of interacting qubits for classical behavior of their macroscopic variables

It is shown that the conditions for classical behavior, in the sense of zero dispersion of all macroscopic variables, for systems of qubits with different dynamics, depend on whether the interaction is local or global. In the case of local interaction, macroscopic coarse-graining is enough. On the other hand, coarse-grained macroscopic variables of globally interacting large systems of qubits have negligible dispersion only if the system is exposed to some form of the environmental decoherence.