It is well known that the most reliable way to reveal the quantum nature of light is through photon number statistics, since photons exhibiting sub-Poissonian statistics unambiguously demonstrate their quantum behavior. In this paper, we show that gravitons emitted by binary systems can, in principle, exhibit analogous sub-Poissonian statistics. The key idea is that the vacuum state of gravitons may not be the standard Minkowski vacuum but rather a nonclassical state imprinted with the physics of the early Universe, such as inflation. Accordingly, gravitational waves from binary systems provide a means to probe the graviton states generated in the early Universe. As a concrete example, we show that squeezed graviton states originating from inflation can, in principle, imprint nonclassical graviton number statistics on gravitational waves from binary systems. In particular, we identify the frequency range in which the resulting coherent-squeezed graviton state can exhibit sub-Poissonian statistics. A realistic assessment of observational feasibility is left for future work.

Close

PrevNext

View figure in article

• Cosmology
• Gravitational waves