September 26, 2025 – A new experiment using superconducting detectors cooled to near absolute zero opens an entirely new frontier, testing the existence of extremely light dark matter particles, with masses thousands of times smaller than those probed by previous experiments. 

Dark matter, the elusive substance that comprises approximately 85% of the universe’s mass, remains one of the greatest mysteries in physics. Invisible and undetectable by ordinary means, it neither emits nor absorbs light, leaving scientists with only indirect evidence of its existence. For decades, researchers have tried in vain to catch a glimpse of these elusive particles. 

The Quantum Resolution-Optimized Cryogenic Observatory for Dark matter Incident at Low Energy (QROCODILE) is a cutting-edge superconducting detector capable of measuring incredibly faint energy deposits—down to just 0.11 electron-volts, millions of times smaller than the energies usually detected in particle physics experiments. The project was led jointly by the Hebrew University of Jerusalem (HU) and University of Zurich , as well as Cornell University, Karlsruhe Institute of Technology (KIT), and the Massachusetts Institute of Technology (MIT).  

In the experiment reported in the Physical Review of Letters, lasting more than 400 hours, the team recorded a small number of unexplained signals. While these events cannot yet be confirmed as dark matter—they may stem from cosmic rays or natural background radiation—they already allow researchers to set new world-leading limits on how lightweight dark matter particles interact with electrons and atomic nuclei. 

The experiment also revealed the potential to detect the directionality of incoming signals. Since the Earth moves through the galactic halo, dark matter particles are assumed to appear from a preferred direction. Future upgrades could allow scientists to distinguish between true dark matter signals and random background noise, a crucial step toward a definitive discovery. 

According to lead scientist Prof. Yonit Hochberg of the Racah Institute of Physics at the Hebrew University, one of the project’s lead scientists, explains, “For the first time, we’ve placed new constraints on the existence of especially light dark matter. This is an important first step toward larger experiments that could ultimately achieve the long-sought direct detection.” 

The next stage of the project, NILE QROCODILE, will further enhance the detector’s sensitivity and move the experiment underground to shield it from cosmic rays. With improved shielding, larger detector arrays, and even lower energy thresholds, the researchers aim to push the boundaries of our understanding of the dark universe. 

 The research paper titled “First Sub-MeV Dark Matter Search with the QROCODILE Experiment Using Superconducting Nanowire Single-Photon Detectors” is now available in Physical Review Letters  and can be accessed here. 

 

Researchers: 

Laura Baudis1, Alexander Bismark1, Noah Brugger1, Chiara Capelli1, Ilya Charaev1, Jose Cuenca García1, Guy Daniel Hadas2, Yonit Hochberg2,3, Judith K. Hohmann4,5

Institutions: 

  1. Department of Physics, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland 
  2. Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel 
  3. Laboratory for Elementary Particle Physics, Cornell University, Ithaca, New York 14853, USA 
  4. Karlsruhe Nano Micro Facility (KNMFi), Engesserstrasse 5, 76131 Karlsruhe, Germany 
  5. Karlsruhe Institute of Technology, Engesserstrasse 5, 76131 Karlsruhe, Germany 
  6. Center for Theoretical Physics – a Leinweber Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA