Space-based cm/kg-scale Laser Interferometer for Quantum Gravity
Abstract
The experimental verification of the quantum nature of gravity represents a milestone in quantum gravity research. Recently, interest has grown for testing it via gravitationally induced entanglement (GIE). Here, we propose a space-based interferometer inspired by the LISA Pathfinder (LPF). Our design employs two kg-scale gold-platinum test masses which, unlike in the LPF, are surrounded by a shield below 1 K and positioned side-by-side with a centimeter-scale separation. This configuration enables the detection of GIE through simultaneous measurements of differential and common-mode motions. To estimate the integration time required for GIE detection, we simulate quantum measurements of these modes, considering noise sources such as gas damping, black-body radiation, and cosmic-ray collisions. Our results show that GIE can be demonstrated with a few modifications to the LPF setup.
Cite
@article{arxiv.2507.12899,
title = {Space-based cm/kg-scale Laser Interferometer for Quantum Gravity},
author = {Nobuyuki Matsumoto and Katsuta Sakai and Kosei Hatakeyama and Kiwamu Izumi and Daisuke Miki and Satoshi Iso and Akira Matsumura and Kazuhiro Yamamoto},
journal= {arXiv preprint arXiv:2507.12899},
year = {2025}
}
Comments
Major revision: The gravitational coupling was recalculated with a corrected form factor, reducing it by half. This tightened the required Gamma*T and lowered the optimal optomechanical coupling. The frequency was reduced to recover the signal, cutting laser power by 21x, which lowers the achievable temperature, enabling 10 g-1 kg masses and 40 day GIE verification