Time: 17. March 2017
Place: Institute of Physics
Title: Quantum entanglement between gravity and matter
We show that gravitational and matter fields are always entangled, as a consequence of local Poincare symmetry. This entanglement is not of dynamical origin, as is common for interacting quantum systems, but rather of kinematical origin, enforced by gauge symmetry at the quantum level. We will give a general argument why one should expect the symmetry-protected entanglement in quantum gravity theories, and then support it by demonstrating explicitly that the Hartle-Hawking state is entangled, in the framework of the Regge quantum gravity model. These results may have various interesting consequences, including the universal gravitational decoherence of matter and a possible small violation of the weak equivalence principle.