  In quantum mechanics, useful experiments require multiple measurements
performed on the identically prepared physical objects composing experimental
ensembles. Experimental systems also suffer from environmental interference,
and one should not assume that all objects in the experimental ensemble suffer
interference identically from a single, uncontrolled environment. Here we
present a framework for treating multiple quantum environments and fluctuations
affecting only subsets of the experimental ensemble. We also discuss a
kinematic effect of indistinguishability not applicable to closed systems. As
an application, we treat inefficient photon scattering as an open system. We
also create a toy model for the environmental interference suffered by systems
undergoing Rabi oscillations, and we find that this kinematic effect may
explain the puzzling Excitation Induced Dephasing generally measured in
experiments.
