Abstract: I will discuss our recent idea for indirectly detecting gravitons. We derive a Langevin equation for a system of a macroscopic object surrounded by gravitons and identify the graviton-induced noise in the system. We propose an experiment where the entanglement between two macroscopic mirrors suspended at the ends of an equal-arm interferometer is destroyed by graviton noise through bremsstrahlung.
By calculating the noise correlation function, we obtain the decoherence time from the decoherence functional. We estimate that the decoherence time induced by graviton noise in squeezed states stemming from inflation is approximately 20 seconds for 40 km long arms and 40 kg mirrors. Our analysis suggests that observing the decoherence time of quantum entanglement has the potential to indirectly detect gravitons.