Toward integrated photonic fusion gates for high-rate time-bin cluster state generation

Highly entangled photonic cluster states have emerged as an important resource for realizing numerous quantum technologies, including measurement-based quantum computing and loss-tolerant quantum networking. We design and fabricate an integrated photonic circuit composed of 2x2 3dB couplers, electro-optic switches, and delay lines on thin-film lithium niobate that can be used to manipulate time-bin photonic qubits. The circuit operates at telecommunication wavelengths, compatible with existing low-loss optical fiber networks. We measure and discuss the impact of important figures of merit for cluster state generation including insertion losses and switch extinction ratios.