We present a class of systems in which a particle - antiparticle pair cannot annihilate each other after they have moved along a loop, and instead form a new type of composite particle. This occurs in so-called non-Hermitian systems; classical metamaterials or "open" quantum systems that are coupled to the rest of the universe. Lukas Königis a PhD Student at Fysikum and is part of the research group Quantum and Complex Systems.
Braid Protected Topological Band Structures with Unpaired Exceptional Points. Illustration: Lukas König
In two dimensions, their excitations are massless "particles" that can be created as a pair, or annihilate each other pairwise. Each particle is associated with the mathematical structure of a knot in a rope. After moving one particle along a loop, and bringing it near its former antiparticle, their knots are combined differently. The two can no longer annihilate pairwise and instead form a new particle corresponding to a more complicated knot. This shows that non-Hermitian particles in two dimensions remember their movement history.
This project brings together several frontiers of basic science - from materials science and quantum optics to the theory of topological phases and modern mathematics - with a potential to provide a basis of future technology.
In this theoretical project, we intend to investigate what happens when we assemble exotic topological components. More specifically, we want to investigate four types of "sculptured topological heterostructures" as briefly described below.
This project focuses on frontiers of topological matter such as non-Abelian anyons from twists and defects in Moiré heterostructures and topological phenomena in open dissipative systems.
The Bergholtz group explores the world of quantum and complex systems — what it is and what it could be — from the perspective of mathematics and theoretical physics.
