Decoherence of Cosmological Perturbations from Boundary Terms and the Non-Classicality of Gravity

Understand

We note that the decoherence of inflationary curvature perturbation $\zeta$ is dominated by a boundary term of the gravity action.

• Although this boundary term cannot affect cosmological correlators $\left\langle \zeta^n \right\rangle$, it induces much faster decoherence for $\zeta$ than that of previous calculations.
• The gravitational origin of inflationary decoherence sheds light on the quantum (or non-classical) nature of gravity.
• By comparing with a Schr\"odinger-Newton toy model of classical gravity, we show that gravity theories of classical or quantum origins can be distinguished by comparing their different impacts on decoherence rate of $\zeta$.