Time Interfaces: Metamaterials that Enable Photon Collisions

Researchers at the City University of New York have discovered that photons, when interacting with metamaterials known as time interfaces, can collide as if they were physical objects. This breakthrough has several potential applications in wireless communications, imaging, and energy harvesting technologies.

In general, photons, which are electromagnetic waves, pass through each other without colliding. However, when they scatter off a lossy structure, they can interfere and exchange energy. This phenomenon, known as coherent wave control, can be utilized to create perfect absorption and control the amount of absorption as needed.

Building on this knowledge, physicist and engineer Andrea Alù and his team have created a new form of control over energy exchanges between photons. They achieved this by using metamaterials that can undergo abrupt and significant changes in their electromagnetic properties, creating a structure called a time interface.

When two waves propagating in opposite directions overlap with a time interface, they experience rapid energy exchanges, as if they were colliding objects. The relative phase of the waves determines the nature of this collision, whether energy is conserved, dissipated, or amplified. This temporal coherent wave control allows for destructive interference and cancellation of waves under specific conditions.

The researchers also discovered that this photonic analogue of mechanical collisions could be used to shape electromagnetic pulses by colliding them against each other. They have successfully demonstrated this in the microwave regime and aim to extend their experiments to higher frequencies.

This research opens up new possibilities for manipulating photons and controlling their behavior. Further developments in this field could revolutionize wireless communications, improve imaging systems, and enhance energy harvesting technologies.

Source: Nature Physics (no URL provided)