Scientists have known for generations that light behaves as both a particle and a wave. Photographs have shown light behaving as one or the other, but never both simultaneously. That changed with a groundbreaking study by Brett Barwick, assistant professor of physics, and Erik Quiñonez ’14, in collaboration with researchers from Switzerland’s École Polytechnique Fédérale de Lausanne (EPFL).

Barwick and Quiñonez, who contributed to the research when he was an undergraduate student, collaborated with their counterparts in Switzerland, led by Fabrizio Carbone, Barwick’s former colleague at the California Institute of Technology. A Faculty Research Committee grant made it possible for the pair to go to the EPFL for portions of their research. Their paper, “Simultaneous observation of the quantization and the interference pattern of a plasmonic near-field,” was published by Nature Communications in March.

Erik Quinoñez ’14, Pratistha Shakya ’15, and Assistant Professor of Physics Brett BarwickPhoto by John Atashian

Erik Quinoñez ’14, Pratistha Shakya ’15, and Assistant Professor of Physics Brett Barwick
Photo by John Atashian

“It was really exciting to do an experiment that captures both the wave and particle aspects of light in a single image,” Barwick said, “and it was particularly satisfying to see a Trinity undergrad, Erik, work with graduate students and postdocs at the EPFL and have the final results end up in Nature Communications.”

The experiment involved hitting a nanowire with short pulses of a laser light. When the light hit the nanowire, it was confined by its very small size and created a standing wave of a particular form of light called a “surface plasmon polariton.” They then shot a stream of electrons near the wire that interacted with the light on the nanowire. With a transmission electron microscope, the team was able to observe the behavior of electrons in the near field around the wire behaving as both a wave and a particle.

News of the study was picked up by media around the world, including The New York Times and Popular Science.

The paper was a collaboration among Trinity’s Department of Physics, the Laboratory for Ultrafast Microscopy and Electron Scattering of EPFL, and the Physical and Life Sciences Directorate of the Lawrence Livermore National Laboratory.

Two weeks before the publication in Nature Communications came out, another paper, titled “Creating electron beams with light,” detailing how electron vortex beams can be created with light, was published in Optics Express, with Trinity alumni Jonathan Handali ’13 and Pratistha Shakya ’15 as co-authors with Barwick.