Matter Mediates Ultrastrong Coupling Between Light Particles
A team of researchers has developed a new way to control light interactions using a specially engineered structure called a 3D photonic-crystal cavity that could enable transformative advancements in quantum computing, quantum communication and other quantum-based technologies.
"Imagine standing in a room surrounded by mirrors," said Fuyang Tay, an alumnus of Rice's Applied Physics Graduate Program and first author of the study. "If you shine a flashlight inside, the light will bounce back and forth, reflecting endlessly. This is similar to how an optical cavity works - a tailored structure that traps light between reflective surfaces, allowing it to bounce around in specific patterns."
These patterns with discrete frequencies are called cavity modes, and they can be used to enhance light-matter interactions, making them potentially useful in quantum information processing, developing high-precision lasers and sensors and building better photonic circuits and fiber-optic networks. Optical cavities can be difficult to build, so the most widely used ones have simpler, unidimensional structures.
[...] "It is well known that electrons strongly interact with each other, but photons do not," said Junichiro Kono, the Karl F. Hasselmann Professor in Engineering, professor of electrical and computer engineering and materials science and nanoengineering and the study's corresponding author. "This cavity confines light, which strongly enhances the electromagnetic fields and leads to strong coupling between light and matter, creating quantum superposition states - so-called polaritons."
[...] If the interaction binding photons and electrons into polaritons is extremely intense - to the point where the exchange of energy between light and matter happens so fast it resists dissipation - a new regime comes into effect known as ultrastrong coupling.
"Ultrastrong coupling describes an unusual mode of interaction between light and matter where the two become deeply hybridized," said Tay, who is currently a postdoctoral researcher at Columbia University.
[...] "This matter-mediated photon-photon coupling can lead to new protocols and algorithms in quantum computation and quantum communications," Kono said.
[...] By providing a new approach to engineering light-matter interactions and ultrastrong photon-photon couplings, the research findings pave the way for the development of hyperefficient quantum processors, high-speed data transmission and next-generation sensors.
Journal Reference: Tay, F., Mojibpour, A., Sanders, S. et al. Multimode ultrastrong coupling in three-dimensional photonic-crystal cavities. Nat Commun 16, 3603 (2025). https://doi.org/10.1038/s41467-025-58835-x
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