On Thursday, August 7, 2025, “Workshop on high-frequency gravitational waves (in the kHz–GHz range)” was held, co-hosted by Adopting Sustainable Partnerships for Innovative Research Ecosystem (ASPIRE), International Center for Quantum-field Measurement Systems for Studies of the Universe and Particles (WPI-QUP), and Institute of Particle and Nuclear Studies (IPNS, KEK).

In recent years, high-frequency gravitational waves (HFGWs) have attracted growing attention as a novel observational tool for probing the early universe. This workshop brought together researchers from theoretical and experimental fields to discuss how various phenomena in the early universe, such as reheating, primordial black holes, and quantum behavior, can be probed through HFGW.The meeting was held at the Tsukuba Campus of the High Energy Accelerator Research Organization (KEK), with an emphasis on lively face-to-face discussions. Approximately 30 people gathered in the conference room, without remote connections, and engaged in heated discussions using whiteboards.

QUP Principal Investigator: Masaya HASEGAWA, one of the organizers, remarked:
"Through this workshop, I was reminded again that high-frequency gravitational waves carry extremely rich information about the early universe. At the same time, I realized that this is still a developing field theoretically, and we can expect many new insights and discoveries. On the experimental side, the challenge lies in detecting extremely weak signals, which require advanced quantum measurement technologies. At QUP, we have already begun research in this area, and this workshop reaffirmed that this is indeed a research domain that aligns perfectly with QUP’s mission."

Related link:
One day workshop on High Frequency Gravitational Waves
https://sites.google.com/view/hfgw2025