Coherent network-driven rotationally symmetric stacked metasurfaces for arbitrary polarization compatibility:...

We propose a coherent control network for arbitrary polarization states and phases. The network is based on a rotationally symmetric stacked metasurface structure that enables XOR, AND, and OR logic operations across dual communication bands via all-optical phase modulation. Stack rotational symmetry gives the structure a polarization-independent response at two-beam incidence, while the coherent control network can precisely modulate the resonant absorption effect between the incident polarization and the metasurface through phase manipulation. Here, we apply this specialized metasurface to a quantum key distribution (QKD) system and successfully design a hybrid encoding mode that utilizes three optical dimensions-polarization, phase, and wavelength. This allows Alice and Bob to modulate 20 polarization states, increasing the information capacity by a factor of 5 compared to the traditional BB84 protocol. Our research significantly improves the performance of metasurfaces in arbitrary polarization multiplexing and phase manipulation and broadens the information dimension of the QKD system in polarization optics.