On Wednesday, February 26, 2025, Dr. Ryota Hayakawa, a postdoctoral fellow at the International Center for Quantum-field Measurement Systems for Studies of the Universe and Particles (WPI-QUP) at KEK, participated as a speaker at the "Sui-Yoru Science Café (Science Café on Wednesday)," an event organized by the Tsukuba Science Tour Office.

His talk was titled "A Thermometer to Measure a Single Photon—Cutting-edge Sensors to Explore the Frontiers of Astronomical Measurements." Ms. Yumi Aoki from the Public Relations Office of the High Energy Accelerator Research Organization (KEK) facilitated the event.

At the beginning of the session, Dr. Hayakawa introduced himself, sharing his background, hobbies, and an overview of his research themes. He also spoke humorously about his journey to becoming a researcher, the challenges he faced, and the joys of scientific exploration.

On his theme of "Measuring a Single Photon," Dr. Hayakawa first explained, through dialogue with Ms. Aoki, that photons—the quantum units of light—exhibit both particle and wave properties. He further elaborated on the concept of the "thermometer," a detector that captures light and measures its energy. He used many visual slides to explain how the TES (Transition Edge Sensor) works. The sensor is a superconducting device he used for dark matter searches at QUP.

The event was held at the Tsukuba Center Building co-en and attracted approximately 40 participants, including online attendees. During and after the lecture, participants asked a variety of questions, indicating a high level of interest in science. One participant asked if this detector is sensitive to light of a specific energy. Dr. Hayakawa explained that the detector accepts photons of a wide range of energies and is capable of measuring the energy of a single photon with high precision.

Related links
Tsukuba Science Tour Office |"Sui-Yoru Science Café " (Japanese)
https://www.i-step.org/tour/news/news_i949_u1.html

KEK｜"Hayakawa will take a stage at Sui-Yoru Science Café " (Japanese)
https://www.kek.jp/ja/event/202502261900sciencecafe