Integration and control of an LNOI interferometer for photonic quantum computing

Photonic quantum computing is a promising platform for achieving high-performance quantum information processing. For system integration and scalability, we propose a solution based on an integrated lithium niobate on insulator (LNOI) platform for optical modulation, presenting an 8-mode LNOI interferometer chip with electro-optic modulators, featuring both electrical and optical coupling. With measured propagation losses of approximately 2 dB/m for straight waveguides, the LNOI platform demonstrates strong potential for scalable and efficient on-chip modulation, connected with ultra-high numerical aperture (UHNA) fibers and wire bonds, and controlled via an FPGA platform. The challenge of low-loss coupling between optical fibers and the photonic chip we have conducted several design studies and experimental investigations, with further work planned to minimize coupling losses <<1dB. The approach includes integrated mode field adapters based on three-dimensional tapers on the chip side, and external geometries for mode matching between fiber and waveguide. These include the use of lensed fibers, UHNA fibers, spot-size converters, and two-photon polymerized microlenses.