Observation of photonic spin-momentum locking due to coupling of achiral metamaterials and quantum dots

Chiral interfaces provide a new platform to execute quantum control of light-matter interactions. While there are reports of spin-momentum locking with combination of chiral emitters or chiral metamaterials it is not readily observable with both achiral emitters and metamaterials. We observe [1] clear signatures of directional and chiral emission from the hybrid system in wavevector resolved emission map in experiments. We report a new regime of spin-momentum locking phenomenon where extrinsic pseudo helicity of light is provided by coupling quantum emitters to evanescent high wavevector modes of hyperbolic metamaterials (HMM) using standard normal incidence illumination. Efficient coupling between quantum dots (QD) and the metamaterial leads to emergence of these photonic topological modes which can be detected in the far field. We provide theoretical explanation for the emergence of spin-momentum locking through rigorous modeling based on photon Green’s function where pseudo spin of light arises from coupling of QD to evanescent modes of HMM.
1. Ravindra K Yadav et al, J Phys. Condens. Matt. 33, 015701 (2020)