In this project, we have proposed a new avenue by introducing metasurfaces to on-chip couple with QEs, which can efficiently outcouple the QEs-excited nonradiative surface plasmon polaritons to photon emission encoded with specific spin and orbital angular momenta (SAM and OAM), respectively. We have realized independent manipulation of the single-photon SAM and OAM states by using metasurface dimers of orthogonal nanobricks that generate (by scattering) high purity SAM (98% for S3 > 0.9). By arranging the nanobrick dimers along different metasurface trajectories controlling OAM, high-purity SAM states are superimposed with OAM states corresponding to different phase-front helicities, for example, l = 0, 1, and 2. Furthermore, we have demonstrated the generation of high-purity linearly polarized (LP) single-photon vortex beams. Remarkably, the design strategy enables simultaneous generation of high-purity orthogonal LP single-photon beams with arbitrary different OAMs, meeting thereby growing demands for increasing the quantum information channel capacity. Thus, by selectively covering azimuthally different metasurface areas with differently arranged nanobricks, we realize multiplexing of single-photon emission channels with orthogonal LPs carrying different topological charges (OAMs) and confirm their entanglement.
Moreover, we have developed the vectorial scattering holography approach, as an inverse design method, with both single-channel and multiple-channel regimes for flexibly designing versatile on-chip QE-coupled metasurfaces. Based on the proposed approach, we design, fabricate, and characterize on-chip quantum light sources of two well-collimated single-photon beams propagating along different off-normal directions with orthogonal linear polarizations. Furthermore, we experimentally demonstrate on-chip generation of multichannel quantum emission encoded with different SAMs and OAMs in each channel. The multichannel holography approach is further extended for tempering the strength of QE emission into a particular channel. The holography-based inverse design approach developed and demonstrated on-chip quantum light sources with multiple degrees of freedoms enable thereby a powerful platform for quantum nanophotonics, especially relevant for advanced quantum photonic applications, e.g. high-dimensional quantum information processing.
In summary, with above achievements, we have published 7 peer-reviewed papers in high-impact journals (all of them are JCR Q1), including Science Advances (selected as cover), Nature Communications, Advanced Materials, and ACS Nano. I have also attended four international conferences and given oral talks, including two invited talks.
