Researchers at Rensselaer Polytechnic Institute (RPI) have created a new and unusual state of matter — known as a supersolid — by engineering how light and matter interact inside a nanoscale device. The work, published in Nature Nanotechnology, demonstrates that this exotic quantum phase can exist at room temperature, overcoming a long-standing limitation in the field. 

Supersolids are unusual because they combine two seemingly incompatible properties: Like a solid, they form an ordered, crystal-like structure. At the same time, they behave like a fluid, meaning they can flow without resistance. Until now, such states have only been observed under extremely cold conditions, close to absolute zero. 

“Our work shows that you can create and control this exotic state using light,” said Wei Bao, Ph.D., assistant professor in the Department of Materials Science and Engineering at RPI and senior author of the study. “What’s especially exciting is that it happens at room temperature, in a platform that can be engineered and potentially scaled.” 

Turning light into a structured quantum fluid 

The research team built a device by combining a high-quality perovskite crystal — a semiconductor material widely studied for optoelectronics — with a precisely patterned nanostructure that traps and shapes light. “We carefully controlled the fabrication process at the nanoscale to ensure the device could reliably confine light and behave as designed,” said co-lead author Wei Li, who is a senior Ph.D. student in Bao’s lab. 

When illuminated by a laser, the system produces hybrid particles called polaritons, which are part light and part matter. These particles can behave collectively, forming a coherent quantum fluid. 

At low excitation power, the polaritons condense into a single, well-defined state. But as the input energy increases, the system undergoes a dramatic transformation. Instead of remaining uniform, it spontaneously reorganizes into a striped pattern — like a crystal — while still maintaining quantum coherence across the entire system. 

“This is the defining feature of a supersolid,” Bao said. “The system is both ordered and coherent at the same time.” 

A self-organizing quantum transition 

Unlike ordinary solids, which form through equilibrium processes such as cooling, the supersolid in this experiment emerges dynamically. 

As more energy is pumped into the system, different quantum states begin to compete. Beyond a critical threshold, the system can no longer stay in a single state and instead redistributes into multiple synchronized states. This competition leads to the formation of a stable, periodic pattern. 

Remarkably, the exact pattern varies from one measurement to the next. 

“Each time we repeat the experiment, the system chooses a slightly different configuration,” Bao said. “That randomness is actually very important: It tells us the pattern is forming spontaneously, not being imposed from outside.” 

“It’s exciting that our optical measurements let us observe this distinctive phase transition simultaneously in the emission spectrum and in real space,” said Yilin Meng, a Ph.D. student in Bao’s group and a co-lead author. “By synchronizing the laser pulses with single-shot real-space imaging, we can confirm that the variations are genuinely random and directly visualize different phase selections from run to run.” 

 Making quantum phenomena more accessible 

One of the most significant aspects of the discovery is that it occurs at room temperature in a compact, chip-scale device. 

In the past, studying supersolids required complex setups operating at temperatures near absolute zero. By contrast, the RPI platform allows researchers to explore these quantum phenomena under much more practical conditions. 

“This gives us a new way to study how complex quantum order emerges in nonequilibrium driven systems,” Bao said. “It brings phenomena that were once limited to specialized laboratories into a more accessible and controllable setting.” 

Toward new light-based technologies 

Beyond its fundamental significance, the work could have practical implications for photonics and quantum technologies. 

Because the supersolid state involves coherent light emission across multiple modes, it could enable new types of lasers with tunable spatial patterns or improved performance. The ability to dynamically control these patterns may also find applications in optical computing and information processing. 

The researchers note that their platform can be extended to create more complex geometries, potentially enabling the study of richer quantum behaviors, including vortex dynamics and other collective phenomena. 

“This is just the beginning,” Bao said. “We now have a platform where we can not only observe these exotic states, but also design and control them. That opens up many exciting directions for both fundamental science and future technologies.” 

This work was mainly supported by the U.S. Army Research Office, National Science Foundation, DARPA, and the Office of Naval Research.