A study conducted at the University of Birmingham has identified the precise shape of a single photon, reshaping how interactions between light and matter at the quantum level are understood. The study detailed in Physical Review Letters tells us how photons, or particles of light, are emitted and influenced by their surroundings, offering possibilities for significant technological advancements.

This achievement stems from addressing a longstanding challenge in quantum physics: the near-infinite ways photons can propagate in their environment. Researchers grouped these scenarios into manageable sets, enabling a model to describe not just how photons interact with their emitters but also how energy radiates into the far field. The findings also included the first-ever visualisation of a photon, achieved through complex calculations.

Complex Problems Made Solvable

Dr Benjamin Yuen, a physicist at the University of Birmingham and lead author of the study, explained that the team converted an otherwise insurmountable problem into a computationally solvable framework. As a result, they could depict the shape of a photon—a significant milestone in quantum physics.

Photon Emission Shaped by Environment

The study, published in the Physical Review Letters, also reveals the critical role of environmental factors, including geometry and optical properties, in defining a photon’s characteristics. According to Professor Angela Demetriadou, co-author of the research, these influences extend to the photon’s colour, shape, and likelihood of being emitted. The data, previously dismissed as background noise, now serves as a valuable source of information.

Advancing Light-Matter Applications

This discovery is expected to advance the design of nanophotonic technologies. Dr. Yuen highlighted its potential to develop improved sensors, solar cells, and systems for quantum computing. A more detailed understanding of light-matter interactions could also lead to breakthroughs in secure communication and molecular-level chemical processes.

By visualising a photon for the first time, the research establishes a foundation for future exploration, marking a significant step forward in understanding the quantum world.