Imagine a type of matter where particles are arranged in a neat crystal pattern but can flow without friction. This peculiar state is called a supersolid, requiring particles to share a common phase and self-organize to minimize their energy.
Although the concept of a supersolid has existed for over 50 years, experiments have only recently provided solid proof. Researchers mainly used ultracold atomic Bose-Einstein condensates (BECs) combined with electromagnetic fields to achieve this.
Scientists have turned light into a supersolid for the first time in a groundbreaking new study. This milestone is a significant leap forward in condensed matter physics.
Dimitrios Trypogeorgos from Italy’s National Research Council (CNR) expressed excitement, saying it’s incredible that they made light solid.
Study shows how to cool an atomic gas into a supersolid
The idea came from earlier work by CNR scientist Danielle Sanvitto, who showed over a decade ago that light could act like a fluid. This idea was later expanded to create a quantum supersolid.
In their experiment, researchers used the semiconductor aluminum gallium arsenide and a laser instead of ultracold atoms. They shone the laser onto a small piece of the semiconductor with narrow ridges. Complex interactions between the light and the material created hybrid particles called polaritons. The ridge pattern controlled how these “quasiparticles” moved and their energies, forming a supersolid.
The researchers carefully measured the trapped and transformed light to prove it was both a solid and a fluid with no viscosity. This was challenging since no one had ever created and tested a supersolid made from light before.
They measured the density changes in the polaritonic state, showing a precise breaking of symmetry. They also had direct access to the wavefunction phase, which allowed them to measure the supersolid’s local coherence with high accuracy.
Quantum liquid becomes solid when heated
Authors noted, “We demonstrated evidence of an out-of-equilibrium supersolid state of matter emerging in a driven-dissipative polaritonic system that is a new and flexible platform for investigating the physics of supersolidity in condensed-matter systems.”
“We emphasize that this is a new mechanism for the creation of a supersolid, particularly of the driven-dissipative context of non-equilibrium polariton systems, and not simply a photonic analog of mechanisms demonstrated in atomic platforms.”
Journal Reference:
Trypogeorgos, D., Gianfrate, A., Landini, M. et al. Emerging supersolidity in photonic-crystal polariton condensates. Nature (2025). DOI: 10.1038/s41586-025-08616-9