Quantum Particle Prediction for Light Emitters and Photonic Devices

Researchers at the University of Oklahoma recently predicted the existence of a new type of particle exciton that could potentially lead to the advancement of future quantum devices. They published their work, the “Theory of topological exciton insulators and condensates in flat Chern bands,” in the journal Proceedings of the National Academy of Sciences.

Excitons are created when electrons and holes they form, bind together. They’ve been observed in insulators and semiconductors, but Bruno Uchoa, a professor of condensed matter physics, and Hong-yi Xie, a postdoctoral fellow in condensed matter physics, are predicting the existence of a new type of exiton with finite vorticity existing in a class of materials known as Chern insulators. They call it a “topological exciton.”

“Chern insulators are materials that allow electrons to orbit the edge of a material but do not conduct any electricity internally,” Uchoa said. “They do, however, spontaneously form unidirectional currents flowing either clockwise or counterclockwise along the edges of a two-dimensional material. These one-way currents are precisely measured in basic units of current.”

Topology is the mathematical study of shape and surface properties that don’t change. It describes materials with electronic properties unaffected by imperfections, and Chern is a class in topology where key characteristics of shapes are represented by whole numbers.

The prediction is that excitons created by shining light through Chern insulators inherit the nontrivial topological properties of the electrons and holes in the host material. This is based on fundamental concepts rather than computer simulations.

The topological excitons could be used when designing a novel class of optical devices, where at low temperatures, they could form a neutral superfluid used to create powerful polarized light emitters or advanced photonic devices for quantum computing. They help develop new optoelectronic devices based on topology,” Uchoa said. “Not only could it aid in quantum communication applications, but it could also help engineer qubits that have two entangled states, on and off, based on the vorticity or polarization of the emitted light. I’m very excited about these possibilities.”