  The impact of disorder in the vibrational bath of an ensemble of open quantum
systems is explored, arising either from variation in the overall coupling
strength or from uncertainty in the shape of the environment spectral function.
Such disorder leads to an additional source of decoherence of subsystem
ensembles, due to variation in the reorganization energy. Additionally,
vibrational disorder induces a shift in the oscillation frequency of the
coherence between ground and excited states. This shift is temperature
dependent, and in the high temperature limit $\delta \omega \propto T$. This
latter finding could be of particular relevance to biological systems
exhibiting long lived coherences in highly disordered environments, where
temperature-dependent quantum beats have been observed.
