New forms of photons open doors 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 electrons that surround atoms, while also being much easier to control.

These new insights have broad applications, from smart LED lighting to new photonic bits of information controlled by quantum circuits, to sensitive nanosensors. Their results are published in Physical assessment B.

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

‘Whatever wild shape you design’

Researchers from the University of Twente studied these photonic orbitals and found that by carefully designing 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 orbit the small nucleus in 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 any wild shape you 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 confined in a specific 3D nanostructure consisting of tiny pores (a photonic crystal). These voids are intentionally designed to have defects, creating a superstructure that isolates the photonic states from the environment.

Physicists Vos and Lagendijk state: “Given the rich toolbox of nanotechnology, it is much easier to design useful nanostructures with new photonic orbitals than 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 enhance the local density of optical states, which is important for applications in cavity quantum electrodynamics.

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