Toward characterization of time-bin qubits with photonic integrated circuits

The growing field of quantum information promises new capabilities for computation, communication, and sensing across networks of quantum-capable devices. However, quantum bits (qubits) cannot be measured and regenerated (as is standard in the classical internet) without altering their state. Thus, it is necessary to develop technologies for routing photonic qubits in the optical domain without losing information. Progress toward these goals is promising, yet many efforts to date have been limited to simpler network topologies and fiber-based or bulk-optic components, which while commercially available, contribute to large system footprints (~1 m²) and considerable system losses (~10+ dB), limiting practical options for expansion. Photonic integrated circuits promise to be a scalable, efficient, and robust platform for quantum information processing as required for large-scale quantum networks. Their compact, monolithic geometry enables relative stability compared with fiber-based components, and integrated themo- and electro-optic components enable dynamic reconfiguration. I discuss and report on measurements leveraging photonic integrated circuits on a thin-film Lithium Niobate platform for the generation and analysis of time-bin-encoded qubits. Large-scale quantum networks based on these and future integrated photonic devices will enable widespread availability of provably secure communication, high-sensitivity measurement, and exponentially accelerated computing.