Universal momentumtorealspace mapping of topological singularities
Abstract
Topological properties of materials are typically presented in momentum space. Here, we demonstrate a universal mapping of topological singularities from momentum to real space. By exciting Diraclike cones in photonic honeycomb (pseudospin1/2) and Lieb (pseudospin1) lattices with vortex beams of topological charge l, optimally aligned with a given pseudospin state s, we directly observe topological charge conversion that follows the rule l → l + 2s. Although the mapping is observed in photonic lattices where pseudospinorbit interaction takes place, we generalize the theory to show it is the nontrivial Berry phase winding that accounts for the conversion which persists even in systems where angular momentum is not conserved, unveiling its topological origin. Our results have direct impact on other branches of physics and material sciences beyond the 2D photonic platform: equivalent mapping occurs for 3D topological singularities such as DiracWeyl synthetic monopoles, achievable in mechanical, acoustic, or ultracold atomic systems, and even with electron beams.
 Publication:

Nature Communications
 Pub Date:
 March 2020
 DOI:
 10.1038/s4146702015374x
 arXiv:
 arXiv:1908.05633
 Bibcode:
 2020NatCo..11.1586L
 Keywords:

 Physics  Optics;
 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 doi:10.1038/s4146702015374x