Scalar‐Superposition Metasurfaces with Robust Placement of Quantum Emitters for Tailoring Single‐Photon Emission Polarization

Abstract Due to nanometric hotspots in a metallic nanoantenna or phase sensitivities in a metasurface, precise placement of a quantum emitter is rigorously required to tailor single‐photon emission, which considerably increases alignment and fabrication difficulties. Here, a scalar‐superposition metasurface is proposed to achieve robust placement of a quantum emitter and meanwhile tailor the single‐photon emission to a desired polarization (e.g., linear, circular, or elliptical polarization). In this metasurface, the far‐field interference of the scattered fields from all unit nanostructures can be simplified as a scalar‐superposition process. As a result, the emission polarization state is insensitive to the phase or the position of the quantum emitter. The simualtion and experiment show that the placement accuracy of the quantum emitter relative to the center of the metasurface is released to about 3 λ (wavelength), which is dozens of times greater than that in previous works. This high placement robustness together with the deflection effect of emission directions of the metasurfaces further enable to tailor the polarization of multiple single‐photon emission spots. The strategy of the scalar‐superposition metasurfaces with robust placement makes the nanostructure design and alignment easy, and it also might provide new possibilities for realizing multifunctional and novel quantum nanophotonic devices.