Dark matter is an invisible mass holding galaxies together. Its nature remains unknown, but one likely candidate is the axion — an ultra-light particle that barely interacts with matter. To catch it, physicists built a hybrid trap.
The trap consists of a layered transparent resonator. As an axion flies through it, with a tiny probability it transforms into a photon of invisible terahertz radiation. The layers amplify this moment many times. Then rubidium atoms, bloated to gigantic sizes (Rydberg atoms), catch that photon and emit a visible flash. A superconducting nanowire at the output registers even a single quantum. After 10 days of measurements, the detector will probe axions at the level predicted by the quantum theory of strong interactions — QCD axions. This would be the first direct contact with dark matter.
The name 'axion' was inspired by a laundry detergent brand: physicists hoped the particle would 'wash away' inconsistencies in the theory.