Can Light Become Both a Solid and a Liquid?

What if something could behave like a solid and a liquid at the same time? It sounds impossible! A solid keeps its shape, while a liquid flows and changes shape. But scientists have discovered a remarkable quantum state that combines both behaviors, and it involves something surprising: light!

An international research team has created a special form of matter called a supersolid. Even more exciting, they achieved this unusual behavior without needing the extremely cold temperatures that many quantum experiments require.

What Makes a Supersolid So Strange?

Think about an ice cube and a glass of water. Ice has an organized structure, with its particles arranged in a repeating pattern. Water, on the other hand, flows freely and takes the shape of its container.

In the quantum world, things can behave very differently. A supersolid combines the repeating arrangement of a crystal with a property called superfluidity. A superfluid is a special liquid that can flow without the usual internal resistance, called viscosity.

Scientists first proposed the idea of a supersolid during the 1960s. However, experiments confirming this strange state only arrived in 2017, using atoms cooled extremely close to absolute zero, the coldest temperature physically possible.

Making a Supersolid with Light

The new research took a different approach. Instead of relying on extremely cold atoms, scientists used unusual hybrid particles called exciton polaritons.

These particles form when light interacts strongly with matter inside a tiny optical chamber called a microcavity. The resulting particles have characteristics of both light and matter.

The researchers built a special chamber containing liquid crystals and an organic semiconductor. This arrangement allowed light and matter to interact and produce the unusual quantum behavior.

Unlike earlier approaches, the system could work at ordinary temperatures, with the liquid-crystal structures capable of operating at temperatures approaching 60°C. That is a major step toward studying exotic quantum effects without complicated extreme-cooling equipment.

Strange Patterns Revealed the Secret

How did the scientists know they had created a supersolid?

They studied the light coming out of their experiment. When the system entered its supersolid state, researchers observed regularly spaced bright patterns called fringes. These patterns showed that the particles had developed an organized arrangement, much like the repeating structure of a crystal.

But something even stranger happened. Every time a laser pulse excited the sample, the bright patterns appeared in different positions. The system was choosing between several possible arrangements. Scientists call this spontaneous symmetry breaking.

The researchers also observed a repeating pattern in the polarization of light. Polarization describes the direction in which light's electric field oscillates.

Why Could This Discovery Change Technology?

Many quantum experiments need expensive cooling equipment to reach temperatures close to absolute zero. A system that can show unusual quantum behavior at room temperature could make future research and technology more practical.

Scientists believe this discovery could eventually help develop faster light-based computers, advanced optical sensors, and special computing systems inspired by the human brain. These brain-inspired systems are called neuromorphic computers.

The device can also be adjusted using electricity, giving researchers greater control over how light and matter behave.

These technologies are still possibilities for future research, not finished products. But this discovery brings scientists closer to exploring quantum effects in more practical ways.

A Tiny Experiment with Huge Possibilities

There was one unusual challenge: the experimental material gradually reacted with the liquid crystal, so scientists had only a few hours to collect their measurements after preparing each sample.

Despite this difficulty, the international team succeeded in observing this extraordinary state of matter.

It reminds us that the quantum world is full of surprises. Something as familiar as light can help reveal behaviors that seem impossible in everyday life. And who knows what other amazing discoveries scientists will make next?