Physicists Shed Light on Precise Shape of Single Photon

New research from the University of Birmingham explores the nature of photons — individual particles of light — in unprecedented detail.

“The geometry and optical properties of the environment has profound consequences for how photons are emitted, including defining the photons shape, color, and even how likely it is to exist,” said University of Birmingham’s Professor Angela Demetriadou.

The team’s new work shows how photons are emitted by atoms or molecules and shaped by their environment.

The nature of this interaction leads to infinite possibilities for light to exist and propagate, or travel, through its surrounding environment.

This limitless possibility, however, makes the interactions exceptionally hard to model, and is a challenge that quantum physicists have been working to address for several decades.

By grouping these possibilities into distinct sets, the authors were able to produce a model that describes not only the interactions between the photon and the emitter, but also how the energy from that interaction travels into the distant far field.

At the same time, they were able to use their calculations to produce a visualization of the photon itself.

“Our calculations enabled us to convert a seemingly insolvable problem into something that can be computed,” said University of Birmingham’s Dr. Benjamin Yuen.

“And, almost as a bi-product of the model, we were able to produce this image of a photon, something that hasn’t been seen before in physics.”

The work is important because it opens up new avenues of research for quantum physicists and material science.

By being able to precisely define how a photon interacts with matter and with other elements of its environment, scientists can design new nanophotonic technologies that could change the way we communicate securely, detect pathogens, or control chemical reactions at a molecular level for example.

“This work helps us to increase our understanding of the energy exchange between light and matter, and secondly to better understand how light radiates into its nearby and distant surroundings,” Dr. Yuen said.

“Lots of this information had previously been thought of as just noise — but there’s so much information within it that we can now make sense of, and make use of.”

“By understanding this, we set the foundations to be able to engineer light-matter interactions for future applications, such as better sensors, improved photovoltaic energy cells, or quantum computing.”

The work was published in the journal Physical Review Letters.

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Ben Yuen & Angela Demetriadou. 2024. Exact Quantum Electrodynamics of Radiative Photonic Environments. Phys. Rev. Lett 133, 203604; doi: 10.1103/PhysRevLett.133.203604