Coupling Quantum Matter and Gravity
Abstract
In this contribution we deal with several issues one encounters when trying to couple quantum matter to classical gravitational fields. We start with a general background discussion and then move on to two more technical sections. In the first technical part we consider the question how the Hamiltonian of a composite two-particle system in an external gravitational field can be computed in a systematic post-Newtonian setting without backreaction. This enables us to reliably estimate the consistency and completeness of less systematic and more intuitive approaches that attempt to solve this problem by adding `relativistic effects' by hand. In the second technical part we consider the question of how quantum matter may act as source for classical gravitational fields via the semiclassical Einstein equations. Statements to the effect that this approach is fundamentally inconsistent are critically reviewed.
Cite
@article{arxiv.2207.05029,
title = {Coupling Quantum Matter and Gravity},
author = {Domenico Giulini and André Großardt and Philip K. Schwartz},
journal= {arXiv preprint arXiv:2207.05029},
year = {2023}
}
Comments
53+6 pages (main text + references), 1 figure. Invited contribution to the forthcoming book "Modified and Quantum Gravity - From Theory to Experimental Searches on All Scales", eds. C. L\"ammerzahl and C. Pfeifer. v2: Added exercises and concluding remarks; minor reformulations