Groundbreaking research combines PT symmetry with topology, offering new insights into open systems and the potential for advanced technological circuits. Whether describing the orbits of planets or the inner workings of an atom, one of the fundamental paradigms in physics is the conservation of energy: although different forms of energy can be converted into each other, the total amount of energy is generally assumed to be constant over time. . So physicists often try to make sure that the system they are trying to describe does not interact with the environment.

However, as it turns out, if the gain and loss of energy are systematically distributed in such a way that they compensate for each other under all conceivable conditions, the dynamics of the system can also be stable, and this can be achieved by so-called parity. temporal (PT) symmetry: Similar to a video being played and projected simultaneously, but completely similar to the original video—that is, PT is symmetric—the components in the system are arranged to accommodate the light gain variation. and loss due to simultaneous reflection and time reversal. makes the system immutable. PT symmetry is not a purely academic concept, but it has paved the way for a deeper understanding of open systems.

Innovation with PT Symmetry

Fascinating physical phenomena related to PT symmetry are the specialty of Professor Oleksandr Sameit from the University of Rostock. Laser light, in special photonic chips, can mimic the behavior of natural and synthetic materials that resemble periodic lattice structures, making them ideal testing grounds for many physical theories.

Thus, Professor Sameit and his team managed to combine PT symmetry with the concept of topology. Topology studies properties that do not change despite continuous deformation of the underlying system. These features make the system particularly resistant to external factors.

Shameita’s research group uses laser-written photonic waveguides (optical structures written into material with a laser beam) for their experiments. So-called topological insulators are applied in these “light chains”. Zameit explains: “These insulators have attracted great attention in recent years due to their fascinating ability to conduct a flow of electrons or light across their boundaries without loss. Their unique ability to suppress the effects of defects and scattering makes them particularly interesting for all kinds of technological applications.”

New discoveries in the field of topological insulators and open systems

But until now such reliable boundary states were thought to be fundamentally incompatible with open systems. Through their joint efforts, researchers from Rostock, Würzburg and Indianapolis managed to show that the apparent paradox can be resolved by dynamically distributing gains and losses over time.

First author, graduate student Oleksandr Friche, explains: “Light propagating along the boundaries of our open system is like a hiker crossing mountainous terrain. Despite all the ups and downs, they will inevitably reach the original height of the starting point. Similarly, our PT-symmetric topological insulator “The light propagated within the protected edge channel will never be specifically amplified or attenuated and can therefore maintain its average amplitude while enjoying the complete reliability provided by the topology.”

These discoveries are a significant contribution to the fundamental understanding of topological insulators and open systems and could open the door to a new generation of advanced circuits for electricity, light and even sound waves.