Speaker
Description
This talk discusses two scenarios in which quantum systems interact with gravity. The central question is to which extend different descriptions of the (quantum) gravitational sector leave distinct imprints on the effective dynamics of the quantum system, particularly on the resulting decoherence.
The first part considers two quantum mechanical toy models describing a neutrino which propagates in an environment representing gravitational waves. This environment is described by a bath of harmonic oscillators in Schrödinger quantisation. The interaction is realised either through a linear coupling to the oscillators' position operators or to their Weyl elements. The latter provides a first step towards a polymer quantisation, which is unitarily inequivalent to the Schrödinger quantisation and inspired by loop quantum gravity. Within the parameter regime investigated, comparing the resulting neutrino dynamics shows that the decoherence pattern in the oscillation probabilities differs perturbatively between the two models.
The second part focuses on the decoherence of a spatial superposition in the presence of a black-hole horizon. While a horizon with underlying classical geometry yields an unavoidable decoherence of the superposition, the implementation of a minimal area gap for the horizon, interpreted as an effective description of a quantum horizon geometry, suppresses the decoherence. For an area gap of the order of the Planck length squared, the resulting decoherence becomes negligibly small.
Together, these two scenarios illustrate how different descriptions of the (quantum) gravitational sector can leave distinct imprints on decoherence phenomena in quantum systems.