https://doi.org/10.1140/epjc/s10052-025-15148-z
Regular Article - Theoretical Physics
Solar System tests of loop quantum effects: improved bound and comparison with strong-field constraints
1
Purple Mountain Observatory, Chinese Academy of Sciences, 210023, Nanjing, China
2
School of Astronomy and Space Science, University of Science and Technology of China, 230026, Hefei, China
a
This email address is being protected from spambots. You need JavaScript enabled to view it.
Received:
25
August
2025
Accepted:
3
December
2025
Published online:
11
December
2025
Abstract
As an extension of the previous work on Solar System tests of an effective loop quantum black hole, and an attempt to find more stringent constraints on the loop quantum effect, we study its effects on physical experiments and astronomical observations conducted in the Solar System. By considering light deflection, time delay, and Cassini tracking experiments at the second post-Newtonian (2PN) order for light propagation, we find that the parametrized post-Newtonian (PPN) parameter 
in the black hole strictly equals 1. Using supplementary advances for Mercury taken from the EPM2011 and INPOP10a ephemerides, we derive much improved bounds on the black hole, which strengthen constraints on the loop quantum effect by ten times. Since such quantum effects are more likely to be observable in strong-field regimes, we estimate a preliminary bound on the loop quantum effect in these regimes based on results from EHT observations, discuss future prospects of other tests (e.g., extreme mass-ratio inspiral systems), and compare these strong-field constraints with those from the Solar System. It is worth noting that primordial black holes might provide a promising way to identify the loop quantum effect. Solar system experiments are probably not applicable for probing the quantum effect signal.
© The Author(s) 2025
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Funded by SCOAP3.
