Using Topological Photon Chips to Uncover the Secrets of Open Systems

Conservation of energy is a fundamental concept in physics that can be used to explain anything from planetary orbits to the internal workings of individual atoms.

Energy can be converted into other forms, but the overall energy level is usually considered to vary over time. Therefore, when attempting to describe a system, physicists usually pay attention to ensuring that it is isolated from the surrounding environment.

However, if the energy gain and loss are distributed in an orderly manner, so that they cancel each other out in all possible situations, the dynamics of the system can also be stable. This can be ensured through a phenomenon called parity check time symmetry.

All components of the system are carefully arranged to exchange the gain and loss of light through simultaneous mirroring and time reversal, making the system appear unchanged, just like a video played backwards and simultaneously reflected in a mirror, but looking exactly the same as the original video, which means it is PT symmetric.

PT symmetry is not just an academic concept; On the contrary, it opens the door to a more thorough understanding of open systems.

Professor Alexander Szameit from Rostock University specializes in studying interesting physical phenomena related to PT symmetry. Laser can replicate the behavior of artificial and natural materials arranged in periodic lattice structures in their customized photonic chips, making them an excellent platform for testing various physical theories.

Therefore, Professor Szameit and his colleagues successfully integrated the ideas of topology and PT symmetry. Topology is the study of properties that remain unchanged even when the underlying system is constantly deformed. When a system possesses these qualities, it becomes particularly resistant to external influences.

Szameit's team used laser engraved photonic waveguides in their experiments, which are optical structures etched into materials by laser beams.

In these "optical circuits," so-called topological insulators are implemented.
So far, people believe that open systems and this powerful boundary state are fundamentally incompatible. Researchers from Rostock, Vilzburg, and Indianapolis have jointly demonstrated that it is possible to address the apparent paradox by dynamically allocating benefits and losses over time.

These findings may pave the way for the development of new cutting-edge circuits for transmitting sound, light, and even electricity. These findings also represent significant advances in the understanding of topological insulators and open systems.

This study was funded by the German Research Foundation and supported by the Alfred Krupp von Boren and the Halbach Foundation.

Source: Laser Net