The Noise of Gravitons

Understand

We show that when the gravitational field is treated quantum-mechanically, it induces fluctuations -- noise -- in the lengths of the arms of gravitational wave detectors.

• The characteristics of the noise depend on the quantum state of the gravitational field, and can be calculated exactly in several interesting cases.
• For coherent states the noise is very small, but it can be greatly enhanced in thermal and (especially) squeezed states.
• Detection of this fundamental noise would constitute direct evidence for the quantization of gravity and the existence of gravitons.