Multichannel Single-Photon Emissions with on-Demand Momentums by Using Anisotropic Quantum Metasurfaces.

Photon momentums and controls of them are of importance for carrying quantum information and increasing information capacities. It is a great challenge to freely control multiple momentums of single photons based on only phase-dependent schemes in isotropic metasurfaces because the exact manipulations of interference phases and precise alignments between quantum emitters and metasurfaces are involved. Here, an anisotropic metasurface, in which anisotropic rather than isotropic nano-scatterers are arranged anisotropically, is proposed to freely control multiple momentums of single photons. In the metasurfaces, the phase-independent and phase-dependent schemes are used to independently control spin angular momentums (SAMs) and linear momentum (LMs), respectively. The phase-independent scheme allows robust alignment between quantum emitters and metasurfaces. The anisotropic design amends geometrical phases for oblique emissions, providing larger ranges (up to 53°) for tailoring LMs. In experiments, three-channel single-photon emissions with independent SAMs and LMs are demonstrated. The introduction of anisotropic nano-scatterers and anisotropic arrangements of nano-scatterers is a more general design method for metasurfaces, and it could provide more flexibilities to freely and efficiently tailor single-photon emissions. This article is protected by copyright. All rights reserved.