New forms of photons open the door to advanced optical technologies

Researchers from the University of Twente in the Netherlands have gained important insights into photons, the elementary particles that make up light. They ‘behave’ in an astonishingly greater variety than the electrons surrounding atoms, while also being much easier to control.

These new insights have wide-ranging applications from smart LED lighting to novel photonic pieces of information controlled by quantum circuits to sensitive nanosensors. Their results are published in Physical review B.

In atoms, tiny elementary particles called electrons occupy regions around the nucleus in shapes called orbitals. These orbitals give the possibility of finding an electron in a certain region of space. Quantum mechanics determines the shape and energy of these orbitals. Similar to electrons, researchers describe the region of space where a photon is most likely to be found with orbitals.

‘Any wild shape you design’

Researchers at the University of Twente studied these photonic orbitals and found that with careful design of specific materials, they can create and control these orbitals with a wide variety of shapes and symmetries. These results have potential applications in advanced optical technologies and quantum computing.

First author Kozon explains, “In chemistry textbooks, electrons always revolve around the small atomic nucleus at the center of the orbital. So the shape of an electron orbital cannot deviate much from a perfect sphere. With photons, the orbitals can have whatever wild shapes we design by combining different optical materials in designed spatial arrangements.”

Easier to design

The researchers conducted a computational study to understand how photons behave when they are confined to a specific 3D nanostructure composed of tiny pores (a photonic crystal). These cavities are deliberately designed to contain defects, creating a superstructure that isolates the photonic states from the surrounding environment.

Physicists Vos and Lagendijk say: “Given the rich toolbox in nanotechnology, it is much easier to design exquisite nanostructures with new photonic orbitals than it is to modify atoms to realize new electronic orbitals and chemistries.”

Advanced optical technologies

Photonic orbitals are important for the development of advanced optical technologies, such as efficient lighting, quantum computing, and sensitive photonic sensors. The researchers also studied how these nanostructures increase the local density of optical states, which is important for applications in quantum cavity electrodynamics.

They found that structures with smaller defects show greater improvement than those with larger defects. This makes them more suitable for integrating quantum dots and creating networks of single photons.