Superradiant spins show teamwork at the quantum scale

(Press-News.org) When quantum particles work together, they can produce signals far stronger than any one particle could generate alone. This collective phenomenon, called superradiance, is a powerful example of cooperation at the quantum level. Until now, superradiance was mostly known for making quantum systems lose their energy too quickly, posing challenges for quantum technologies. But a new study published in Nature Physics turns this idea on its head— revealing that collective superradiant effects can instead produce self-sustained, long-lived microwave signals with exciting potential for future quantum devices. 

“What’s remarkable is that the seemingly messy interactions between spins actually fuel the emission,” explains Dr Wenzel Kersten, first author of the study. “The system organizes itself, producing an extremely coherent microwave signal from the very disorder that usually destroys it.” 

Researchers from TU Wien (Vienna University of Technology) and the Okinawa Institute of Science and Technology (OIST) have demonstrated the first example of self-induced superradiant masing—spontaneous, long-lived bursts of microwave emission generated without external driving. Their discovery provides a new method for generating highly stable and precise microwave signals, paving the way for technological advances across a variety of important fields, from medicine to navigation and quantum communication. 

“This discovery changes how we think about the quantum world,” says Professor Kae Nemoto, Center Director of the OIST Center for Quantum Technologies. “We’ve shown that the very interactions once thought to disrupt quantum behavior can instead be harnessed to create it. That shift opens entirely new directions for quantum technologies.” 

Collective behavior drives powerful pulses 

To explore how spin systems behave collectively, the researchers coupled a dense ensemble of nitrogen-vacancy (NV) centers in diamond—tiny atomic defects—to a microwave cavity. Each NV center hosts electron spins that can be flipped between quantum states, acting as miniature magnets.  

“We observed the expected initial superradiant burst—but then a surprising train of narrow, long-lived microwave pulses appeared,” explains Professor William Munro, co-author of the study and head of OIST’s Quantum Engineering and Design Unit.  Through large-scale computational simulations, the team identified the source of this pulsing: self-induced spin interactions that dynamically repopulate energy levels, sustaining emission without external pumping. “Essentially, the system drives itself,” adds Prof. Munro. “These spin–spin interactions continually trigger new transitions, revealing a fundamentally new mode of collective quantum behavior.” 

Next-generation quantum technologies  

Beyond uncovering new quantum physics, the findings point toward practical applications. Stable, self-sustained microwave emission could form the basis for ultra-precise clocks, communication links, and navigation systems—technologies that underpin modern life, from GPS and telecommunications to radar and satellite networks. 

“The principles we observe here could also enhance quantum sensors capable of detecting minute changes in magnetic or electric fields,” says Professor Jörg Schmiedmayer of the Vienna Center for Quantum Science and Technology, TU Wien. “Such advances could benefit medical imaging, materials science, and environmental monitoring. More broadly, this work shows how deep insights into quantum behavior can translate into new tools and technologies to shape the next generation of scientific and industrial innovation.”

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