Quantum entanglement remains one of physics’ strangest ideas. Two particles become linked so closely that changing one instantly affects the other, even across large distances. Scientists have studied this effect for years in tiny quantum systems, but controlling it in larger materials has proved much harder. Researchers at Rice University believe they may have found a way to make that process easier.
Physicist Qimiao Si and his collaborators have proposed a method that uses quantum light to retrieve entanglement from quantum materials. The work could help scientists better study exotic materials while supporting future quantum technologies.
The idea involves placing materials inside small mirrored cavities and exposing them to photons, or particles of light. Under the right conditions, the light and matter begin behaving as one connected quantum system.
Near the tipping point
For years, researchers believed they needed extremely strong interactions between light and matter to create these hybrid states. Building systems powerful enough to achieve that has remained difficult.
Si’s team thinks the answer may lie in something called a quantum critical point. This is the stage where a material sits between two quantum phases and becomes highly sensitive to change.
“In this theory, by placing matter in a small mirrored cavity and pushing it towards what is called the quantum critical point, we can then introduce photons and induce quantum entanglement,” Si said.
Researchers can push materials toward this state without heating them. Instead, they can apply pressure or slightly alter the material’s chemical structure. As the material moves closer to its quantum critical point, the threshold needed for entanglement drops sharply.
That makes it easier for photons and matter to lock into the same quantum state. Graduate researcher Yiming Wang explained that the material essentially stands between two different quantum phases. Only at the critical point can it transition into the second phase.
Light follows matter
The theory becomes more useful once the entanglement forms. According to the researchers, the light and material begin reflecting each other’s behavior. If the material changes quantum phases, the photons change as well.
“If the material enters the quantum critical point when entangled to light and transitions to the second phase, the light will transition as well,” said co-author Shouvik Sur.
That connection could give physicists a simpler way to study quantum materials. Scientists could observe both the material and the light leaving the cavity using existing experimental tools.
The work also builds on earlier research from Si’s group involving strange metals, a class of quantum materials known for strong entanglement effects. Researchers have long viewed those materials as promising for advanced quantum devices, but extracting the entanglement remained a challenge.
This new proposal offers a possible solution. Once the photons become entangled with the material, researchers could remove the light from the cavity and study it directly.
The team believes the approach could eventually support technologies like highly sensitive quantum sensors and other next-generation devices. Researchers still need experiments to confirm the theory. Even so, the study offers physicists a clearer path toward controlling quantum entanglement in larger and more practical systems.
