Researchers at the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences have achieved a 100-fold enhancement in the detection of signals potentially linked to dark matter, unveiling the first intercity quantum sensor network dedicated to this elusive substance. Published in Nature on January 28th, the team’s innovative approach utilizes a 320-kilometer network of five nuclear-spin quantum sensors spanning Hefei and Hangzhou, synchronized with GPS time, to search for faint interactions stemming from axion topological defects. This groundbreaking experiment “stores” microsecond-scale signals in a long-lived nuclear-spin state, allowing for minute-scale readout—a feat enabled by a self-developed quantum spin amplification technique. While no definitive dark matter events were recorded over two months, the study establishes the first laboratory experiment to surpass existing astrophysical constraints, opening new avenues for exploring beyond-Standard Model physics.
Axion Topological Defects and Dark Matter Signals
These defects are predicted to interact with atomic nuclei, creating fleeting signals that are notoriously difficult to discern, but the USTC team has developed a system to amplify these interactions. “Stores” of microsecond-scale signals are preserved within long-lived nuclear-spin states, allowing for minute-scale readout. The team’s quantum sensor network, linking Hefei and Hangzhou, achieved a sensitivity increase of approximately four orders of magnitude over previous methods, reaching 1 μrad. Utilizing a self-developed quantum spin amplification technique, they boosted the weak dark-matter signal by at least 100-fold.
While two months of observation yielded no definitive detection of a topological-defect crossing, the experiment established the most stringent constraints yet on axion–nucleon coupling, reaching 4.1 × 1010 GeV at 84 peV. This breakthrough opens avenues for exploring previously inaccessible parameter space and investigating broader beyond-Standard Model physics.
Intercity Quantum Sensor Network Constrains Axion-Nucleon Coupling
The search for dark matter received a significant boost with the deployment of a novel quantum sensor network, pushing the boundaries of detection beyond what astronomical observations currently allow. This setup enabled the team to search for extremely faint signals potentially generated by axions – hypothetical particles comprising a significant portion of dark matter – interacting with nuclear spins. “This study provides the first laboratory experiment to exceed astrophysical constraints on axion topological-defect dark matter,” the team states. Despite observing for two months without detecting a statistically significant event, the experiment yielded crucial results. According to the researchers, this work “opens up the possibility of examining unexplored parameter space” for dark matter and broader beyond-Standard Model physics.
In this experiment, the researchers developed a nuclear-spin quantum precision measurement that “stores” microsecond-scale axion-induced signals in a long-lived nuclear-spin coherent state, enabling a readout signal on the scale of minutes.
Researchers from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences and their collaborators
