Bound on quantum fluctuations in gravitational waves from LIGOVirgo
Abstract
We derive some of the central equations governing quantum fluctuations in gravitational waves, making use of general relativity as a sensible effective quantum theory at large distances. We begin with a review of classical gravitational waves in general relativity, including the energy in each mode. We then form the quantum ground state and coherent state, before then obtaining an explicit class of squeezed states. Since existing gravitational wave detections arise from merging black holes, and since the quantum nature of black holes remains puzzling, one can be openminded to the possibility that the wave is in an interesting quantum mechanical state, such as a highly squeezed state. We compute the time and space twopoint correlation functions for the quantized metric perturbations. We then constrain its amplitude with LIGOVirgo observations. Using existing LIGOVirgo data, we place a bound on the (exponential) squeezing parameter of the quantum gravitational wave state of ζ < 41.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 March 2023
 DOI:
 10.1088/14757516/2023/03/009
 arXiv:
 arXiv:2112.12159
 Bibcode:
 2023JCAP...03..009H
 Keywords:

 gravitational wave detectors;
 gravitational waves / theory;
 Quantum fields in curved spacetimes;
 quantum gravity phenomenology;
 General Relativity and Quantum Cosmology;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory;
 Quantum Physics
 EPrint:
 11 pages, 3 figures, in double column format. V2: Updated introduction and referencing. V3: Updated towards version published in JCAP