Researchers from the University of Twente have found far greater diversity in the behavior of photons compared to electrons surrounding atoms, while also being much easier to control. These new insights have implications for a broad range of technologies, including smart LED lighting, photonic qubits, and sensitive nanosensors, among others. Electrons occupy regions around an atom’s nucleus in shapes called orbitals. These orbitals determine the probability of finding an electron in a particular region of space, while quantum mechanics determines the shape and energy of these orbitals. Similarly to electrons, researchers also describe the region of space where a photon is most likely found with orbitals. Researchers at the University of Twente have found that photonic orbitals can be manipulated by careful material design. The diagram shows several photonic orbitals that arose within a photonic crystal superlattice. Courtesy of University of Twente. In the current work, the researchers studied these photonic orbitals and discovered that with careful design of specific materials, they can create and control these orbitals with a great variety of shapes and symmetries. These results have potential applications in advanced optical technologies and quantum computing. “In textbook chemistry, the electrons always orbit around the tiny atomic core at the center of the orbital. So an electron orbital's shape cannot deviate much from a perfect sphere,” said first author Marek Kozon. “With photons, the orbitals can have whatever wild shape you design by combining different optical materials in designed spatial arrangements.” Photonic orbitals are important for developing advanced optical technologies, such as efficient lighting, quantum computing, and sensitive photonic sensors. The researchers conducted a computational study to understand how photons behave when they are confined in a photonic crystal, a specific 3D nanostructure consisting of tiny pores. These cavities are intentionally designed to have defects, creating a superstructure that isolates the photonic states from the surrounding environment. 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 reveal greater enhancement than those with larger defects. This makes them more suitable for integrating quantum dots and creating networks of single photons. The research was published in Physical Review B (www.doi.org/10.1103/PhysRevB.109.235141).
