Publication of an employee of our Faculty in Nature Physics !!!

The paper "Gain-induced topological response via tailored long-range interactions" by dr inż. Paweł Jung from the Faculty of Physics of the Warsaw University of Technology had the opportunity to prepare thanks to the cooperation with the team of prof. Demetrios Christodoulides from the University of Central Florida (USA) and prof. Mercedeh Khajavikhan from the University of Southern California (USA) as part of a research grant from the Ministry of Education and Science "Mobility Plus". Haldane's 1988 model was implemented for the first time in photonics.

Recent theoretical studies have shown that physical phenomena can occur in quantum systems that lead to counterintuitive effects. One of such phenomena is the presence of asymmetry in short- and long-range interactions between the components of the physical system. The effect of this is, among others the possibility of Kramers degeneration in the absence of energy in the state of the spin 1/2 system.

The article shows that the asymmetric complex long-range interaction between atoms without the presence of an external magnetic field can also be realized in photonic systems. For this purpose, the authors of the study prepared a special waveguide system based on: quantum wells made of InGaAsP semiconductor compounds, ring optical resonators and unidirectional couplers.

The geometry of the system was modeled on the Haldane crystal model, the topology of which resembles honeycombs arranged on a triangular plan. The induction of optical amplification in the system by means of a pulsed laser made it possible to demonstrate the quantum Hall effect without an external magnetic flux.

The presented results indicate the possibility of implementing a wide class of systems with unusual phenomena in the area of topological phases of matter. Moreover, they open up new directions for research on the role of amplification and nonlinearity in topological systems in the presence of quantum noise.

You can read the article at this address (paid access).