A new network to detect the echoes of the hidden Universe is taking shape

The detection of high-frequency gravitational waves (HFGWs) represents the next frontier in the intersection of fundamental physics, astrophysics and metrology. Since the first detection of gravitational waves by LIGO in 2015, scientists have been able to probe the universe in the frequency range from 10 Hz to 10 kHz. However, vast unexplored bands remain, including the MHz to GHz range. Contrary to their lower-frequency counterparts, these bands are characterized by extremely weak backgrounds from known objects, which makes them a perfect messenger of the unknown Universe, in particular of sources connected to some of the most fundamental questions of modern Cosmology: dark matter, inflation or quantum gravity.In March 2025, a team of scientists led by ICREA Prof. Diego Blas, Instituto de Física de Altas Energías, Spain, Prof. Dr. Matthias Schott, Rheinische Friedrich-Wilhelms-University, Bonn, Germany, Prof. Dr. Dmitry Budker, Johannes Gutenberg University, Mainz, Germany, and Dr. Claudio Gatti, National Institute for Nuclear Physics, Italy, funded GravNet: A Global Network for the Search for High-Frequency Gravitational Waves, the first worldwide network of detectors aiming at developing and deploying a novel experimental platform to detect HFGWs.GravNet will be initially funded by an ERC-SYNERGY grant (awarded in 2024) and is based on an innovative use of quantum sensing technologies. The project utilizes cavities in strong magnetic fields to convert gravitational waves into photons. To maximize the chances of detection, GravNet will deploy a network of detectors across multiple European laboratories: Bonn, Mainz, Frascati and PSI. These detectors will be synchronized using a GPS-based data acquisition scheme, enabling them to function as a unified, highly sensitive array.This network is being joined by other institutes worldwide, with the first joint data-taking campaigns expected in 2026. By launching a novel detection program that bridges gravitational wave science with cutting-edge quantum sensing technologies, GravNet will foster collaboration and synergies between these two scientific communities to detect the first traces of the hidden Universe.