Italian scientists have achieved a groundbreaking feat by "freezing" light, revealing that it can exist as a supersolid—a rare state of matter that combines a solid-like structure with frictionless flow. The discovery, recently published in Nature, represents a major advancement in quantum physics and holds the potential to transform future developments in quantum computing and optical technology.

What Is Supersolid Light?

A supersolid is a unique phase of matter that combines the structural rigidity of a solid with the frictionless flow of a superfluid. Previously, supersolidity had only been observed in Bose-Einstein condensates (BECs)—a state of matter that forms when a collection of bosons is cooled to nearly absolute zero, causing them to share the same quantum state. However, researchers led by Antonio Gianfate of CNR Nanotec and Davide Nigro from the University of Pavia have now shown that light can also display this unusual behaviour.
Rather than traditional freezing, where a liquid solidifies by lowering its temperature, the researchers employed quantum techniques to induce a supersolid state in light. They utilised a semiconductor platform specifically designed to control photons in a way that mirrors electron behaviour in conductors.
The team used a gallium arsenide structure embedded with microscopic ridges and fired a laser to generate hybrid light-matter particles called polaritons.
As the photon count increased, they observed the emergence of satellite condensates—a signature of supersolidity. These condensates exhibited identical energy but opposite wavenumbers, creating a distinctive spatial arrangement that confirmed the existence of a supersolid state.
“At temperatures near absolute zero, quantum effects emerge,” the researchers explained. “This is just the beginning of understanding supersolidity in light.”

Significance of the Discovery

This breakthrough holds profound implications for quantum technology. Supersolid light could be instrumental in enhancing the stability of quantum bits (qubits), a key component in advancing quantum computing.
Beyond computing, the ability to control light in this manner could transform optical devices, photonic circuits, and fundamental quantum mechanics research. Scientists expect that further studies will refine these techniques, leading to more stable and precisely controlled formations of supersolid light.