  We discuss recent experimental evidence of decoherence in a laboratory
mesoscopic system in a cavity, from which we draw analogies with the
decoherence that we argue is induced by microscopic quantum-gravity
fluctuations in the space-time background. We emphasize the parallel r\^oles
played in both cases by dissipation through non-trivial vacuum fluctuations
that trigger the collapse of an initially coherent quantum state. We review a
phenomenological parametrization of possible effects of this kind in the
neutral kaon system, where they would induce CPT violation, and describe some
epxerimental tests.
