A groundbreaking discovery by a research team at the Advanced Science Research Center at the CUNY Graduate Center (CUNY ASRC) has revealed the ability to manipulate photons, causing them to collide and interact in new and exciting ways. This breakthrough, published in Nature Physics, holds immense potential for advancements in telecommunications, optical computing, and energy applications.
This groundbreaking research was conducted in the lab of Andrea Alù, Distinguished Professor and Einstein Professor of Physics at The City University of New York Graduate Center, and founding director of the CUNY ASRC Photonics Initiative. It was made possible by a recent experiment demonstrating time-reflections for electromagnetic waves.
“Our work builds upon a series of experiments that have shown how we can create metamaterials with unique properties arising from abrupt time variations in their electromagnetic properties. These variations enable us to manipulate wave propagation in ways not observed in nature,” explained Alù.
“In our latest work, we demonstrate that we can use abrupt temporal changes in tailored metamaterials, known as time interfaces, to make waves collide as if they were massive objects. Furthermore, we can control whether the waves exchange, gain, or lose energy during these collisions.”
Ordinarily, when two electromagnetic waves intersect, they pass through each other without any interaction. This is vastly different from what occurs when two physical objects, such as balls, collide. In such cases, the particles collide, and their mechanical properties determine whether energy is conserved, lost, or increased during the collision. For instance, when two billiard balls collide, the total energy in the system remains constant, while two rubber balls typically lose energy upon collision.
While photons are expected to pass through each other without interaction, the scientists were able to trigger a time interface, resulting in strong photon-photon interactions and control over the collision’s nature.
The inspiration for this research came from speculation about the possibility of erasing an unwanted mechanical wave, like a tsunami or seismic wave, by counteracting it with a similar wave. “Although this outcome is impossible in conventional wave physics, we knew it was theoretically possible with a temporal metamaterial,” said Emanuele Galiffi, a postdoctoral fellow in Alù’s lab and the study’s lead author. “Our experiment allowed us to demonstrate this concept in action for electromagnetic waves.”
The scientists also proposed and demonstrated an application of their concept by shaping electromagnetic pulses through collision. “This technique enables us to use an additional signal as a mold to shape a pulse that we want to structure,” said Gengyu Xu, a postdoctoral fellow in Alù’s lab and co-lead author of the paper. “We have demonstrated this for radio frequencies and are now working towards realizing this shaping ability at higher frequencies.”
The team’s work in developing methods to control the interaction and shaping of propagating electromagnetic waves holds great potential for advancements in wireless communications, imaging, computing, and energy harvesting technologies, among other fields.
