Researchers Unlock Light-Matter Interactions on Subnanometer Scales

Researchers at Purdue University have discovered waves with picometer-scale spatial variations of electromagnetic fields that can propagate in semiconductors like silicon. The findings demonstrate that natural media host a variety of light-matter interaction phenomena at the atomistic level. The use of picophotonic waves in semiconducting materials may lead researchers to design new, functional, optical devices, allowing for applications in quantum technologies.

This figure demonstrates picophotonics in the 3D lattice of silicon atoms. The red wave represents the conventional electromagnetic wave propagating in the solid. The blue inner wave represents the new predicted picophotonic wave. Courtesy of Zubin Jacob/Purdue University.

Over the past decade, nanophotonics — the study of how light flows on the nanometer scale in engineered structures such as photonic crystals and metamaterials — has led to important advances. Existing research in nanophotonics can be captured within the realm of classical theory of atomic matter.

The Purdue team’s finding, leading to picophotonics, falls in the realm of quantum theory of atomistic response in matter.

The team’s work targets a long-standing puzzle in the field: the missing link between atomic lattices, their symmetry, and the role it plays in deeply picoscopic light fields. To solve this puzzle, the team developed a Maxwell-Hamiltonian framework of matter combined with a quantum theory of light-induced response in materials.

“This is a pivotal shift from the classical treatment of light flow applied in nanophotonics,” said Zubin Jacob, Elmore Associate Professor of Electrical and Computer Engineering and Department of Physics and Astronomy. “The quantum nature of light’s behavior in materials is the key for the emergence of picophotonics phenomena.”

Research scientist Sathwik Bharadwaj and colleagues showed that hidden amid traditional well-known electromagnetic waves, new anomalous waves emerge in the atomic lattice. These lightwaves are highly oscillatory even within one fundamental building block of the silicon crystal (subnanometer-length scale).

According to Bharadwaj, natural materials have rich, intrinsic crystal lattice symmetries — and light is strongly influenced by these symmetries. The team’s next goal, stemming from the work, is to apply its theory to quantum and topological materials.

The team also aims to verify the existence of the newly discovered waves experimentally. Further, Jacob said that the team has initiated a picoelectrodynamics theory network that brings together a diverse group of researchers to explore macroscopic phenomena stemming from microscopic pico-electrodynamic fields inside matter.

The research was published in Physical Review Applied (www.doi.org/10.1103/PhysRevApplied.18.044065).