Researchers in Birmingham have created the first images of photons, lemon-shaped particles of light, emitted from the surface of nanoparticles. The theory that made this image possible, reported November 14 in the journal physical review letterallows scientists to calculate and understand various properties of these quantum particles. This can open up a variety of new possibilities across areas such as: quantum computingphotovoltaic devices and artificial photosynthesis.
The quantum behavior of light is well established and has been proven by over 100 years of experiments. Can exist in both wave and particle form. However, our fundamental understanding of this quantum nature is far behind, and we have limited knowledge of how photons are created and emitted, or how they change through space and time. There is only a limited understanding.
“We want to be able to understand these processes in order to take advantage of the quantum aspects,” says first author Ben YuenResearchers from the University of Birmingham, UK, told Live Science in an email. “How do light and matter actually interact at this level?”
However, the very nature of light means that there are nearly infinite possibilities for answering this question. “You can think of photons as the fundamental excitation of electromagnetic fields,” Yuen explained. These fields are a continuum of different frequencies, each of which can potentially be excited. “You can split the continuum into smaller parts, and between any two points there are an infinite number of points you can choose from,” Yuen added.
As a result, the properties of a photon are highly dependent on the properties of its environment, requiring incredibly complex calculations. “At first glance, you would need to write down and solve an infinite number of equations to arrive at the answer,” Yuen says.
To tackle this seemingly impossible task, Yuen and coauthors Angela DemetriadouProfessor of Theoretical Nanophotonics at the University of Birmingham has employed a clever mathematical trick to dramatically simplify the equation.
Introducing imaginary numbers (impossible square root multiples of -1) is a powerful tool when working with complex equations. Manipulating these imaginary components allows many of the difficult terms in the equation to cancel each other out. The computation becomes more manageable if all imaginary numbers are converted back to real numbers before reaching the solution.
“We transformed a continuum of real frequencies into a discrete set of complex frequencies,” Yuen explained. “In doing so, we simplify the continuum equations into discrete sets that we can process. We can input them into a computer and solve them.”
The researchers used these new calculations to model the properties of photons emitted from the nanoparticle’s surface, explaining their interaction with the emitter and how the photon propagates from the source. . From these results, the team generated the first images of photons, lemon-shaped particles never before seen in physics.
But Yuen emphasized that this is just the shape of the photons produced under these conditions. “The shape changes completely depending on the environment,” he said. “This is the real point of nanophotonics: by shaping the environment, you can actually shape the photons themselves.”
The team’s calculations provide fundamental insight into the properties of this quantum particle, and Yuen believes this knowledge will open up new areas of research for physicists, chemists, and biologists alike.
“You can think about optoelectronic devices, photochemistry, light harvesting, photovoltaics, photosynthesis, biosensors, quantum communications,” Yuen said. “And there will be many unknown applications. Putting this kind of really fundamental theory into practice will unlock new possibilities in other fields.”
