2018/12/19 by Lukas J. Maczewsky, Bastian Höckendorf, Mark Kremer +5 · 2 citations
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Enhanced Data Rates for GSM Evolution #Floquet theory #Photonic crystal #Photonics #Quantum and electron transport phenomena #Realization (probability) #Symmetry (geometry) #Topological Materials and Phenomena #Topological insulator #Topology (electrical circuits) #cond-mat.mes-hall #physics.optics
paper · pdf · doi:10.1038/s41563-020-0641-8
published as Nature Materials (2020)
arxiv created 2018/12/19 · openalex created_date 2018/12/22 · openalex publication_date 2020/03/23 · arxiv updated 2020/03/26 · openalex updated_date 2026/08/05
Much of the recent enthusiasm directed towards topological insulators as a new state of matter is motivated by their hallmark feature of protected chiral edge states. In fermionic systems, Kramers degeneracy gives rise to these entities in the presence of time-reversal symmetry (TRS). In contrast, bosonic systems obeying TRS are generally assumed to be fundamentally precluded from supporting edge states. In this work, we dispel this perception and experimentally demonstrate counter-propagating chiral states at the edge of a time-reversal-symmetric photonic waveguide structure. The pivotal step in our approach is encoding the effective spin of the propagating states as a degree of freedom of the underlying waveguide lattice, such that our photonic topological insulator is characterised by a ℤ2-type invariant. Our findings allow for fermionic properties to be harnessed in bosonic systems, thereby opening new avenues for topological physics in photonics as well as acoustics, mechanics and even matter waves.