  With recent developments in high-precision quantum measurements, the question
of whether observations of decoherence from spacetime fluctuations are
accessible experimentally arises. Here we investigate the dynamics of bound
states interacting with an environment of gravitons under the Markov
approximation. The corresponding Lindblad master equation is presented that
enables gravitational decoherence and dissipation due to zero-point spacetime
fluctuations to be analyzed. Specifically, we consider a one-dimensional cavity
of massless scalar particles that models a light beam with negligible spin
polarizations being reflected between two free masses. Numerical simulations
have been performed to illustrate the wave-modal dependent decoherence and
dissipation of such a configuration. We further demonstrate the existence of
nontrivial collective effects akin to superradiance, providing amplifications
of gravitational decoherence for a large number of identical bosonic particles.
