Physicists Show That a Quantum Particle Made of Light and Matter Can Be Dragged by a Current of Electrons – Columbia University

In therecent Nature study, Basov and his colleagues recreated Fizeaus experiments on a speck of graphene made up of a single layer of carbon atoms. Hooking up the graphene to a battery, they created an electrical current reminiscent of Fizeaus water streaming through a pipe. But instead of shining light on the moving water and measuring its speed in both directions, as Fizeau did, they generated an electromagnetic wave with a compressed wavelengtha polaritonby focusing infrared light on a gold nub in the graphene. The activated stream of polaritons look like light but are physically more compact due to their short wavelengths.

The researchers clocked the polaritons speed in both directions. When they traveled with the flow of the electrical current, they maintained their original speed. But when launched against the current, they slowed by a few percentage points.

We were surprised when we saw it, saidstudy co-author Denis Bandurin, a physics researcher at MIT. First, the device was still alive, despite the heavy current we passed through itit hadnt blown up. Then we noticed the one-way effect, which was different from Fizeaus original experiments.

The researchers repeated the experiments over and over, led by the studys first-author, Yinan Dong, a Columbia graduate student. Finally, it dawned on them. Graphene is a material that turns electrons into relativistic particles, Dong said. We needed to account for their spectrum.

A group at Berkeley Lab founda similar result, published in the same issue of Nature. Beyond reproducing the Fizeau effect in graphene, both studies have practical applications. Most natural systems are symmetric, but here, researchers found an intriguing exception. Basov said he hopes to slow down, and ultimately, cut off the flow of polaritons in one direction. Its not an easy task, but it could hold big rewards.

Engineering a system with a one-way flow of light is very difficult to achieve, saidMilan Delor, a physical chemist working on light-matter interactions at Columbia who was not involved in the research. As soon as you can control the speed and direction of polaritons, you can transmit information in nanoscale circuits on ultrafast timescales. Its one of the ingredients currently missing in photon-based circuits.

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Physicists Show That a Quantum Particle Made of Light and Matter Can Be Dragged by a Current of Electrons - Columbia University