  We propose an experiment that the entanglement between two macroscopic
mirrors suspended at the end of an equal-arm interferometer is destroyed by the
noise of gravitons through bremsstrahlung. By calculating the correlation
function of the noise, we obtain the decoherence time from the decoherence
functional. We estimate that the decoherence time induced by the noise of
gravitons in squeezed states stemming from inflation is approximately 20
seconds for 40 km long arms and 40 kg mirrors. Our analysis shows that
observation of the decoherence time of quantum entanglement has the potential
to detect gravitons indirectly. This indirect detection of gravitons would give
strong evidence of quantum gravity.

General Relativity and Quantum Cosmology;High Energy Physics - Phenomenology;High Energy Physics - Theory;Quantum Physics