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 as an undergraduate student, collaborated both remotely and in person with their counterparts in Switzerland, led by Fabrizio Carbone, a former colleague of Barwick’s 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 this month.
“It was really exciting to do an experiment that captures both the wave and particle aspects of light in a single image” said Barwick, “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 hits the nanowire it is confined by its very small size and creates a standing wave of a particular form of light called a “surface plasmon polariton.” They then shot a stream of electrons near the wire, which 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 particle. The high speed of the microscope made the elusive photo possible.
The news of the study was picked up by media across the United States and around the world. The New York Times featured the research in its evening briefing, and science and technology publications around the world, including Popular Science, have highlighted the achievement.
Two weeks before the publication in Nature Communication came out, another paper entitled “Creating electron beams with light”, detailing how electron vortex beams can be created with light was published in Optics Express, with Trinity alumnus Jonathan Handali ’13 and current Trinity student Pratistha Shakya ’15 as co-authors with Barwick.
Both articles are Open Access articles and can be downloaded free from the respective publishers.
“Simultaneous observation of the quantization and the interference pattern of a plasmonic near-field” is a collaboration among Trinity College’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.