Low-Loss Photonic Modulator toward Future Quantum Information Processing

High-fidelity quantum information processing with cascaded photonic integrated circuits demands precise phase control and minimal optical loss at every stage. Low-loss phase modulators therefore constitute a critical component, directly governing quantum coherence, interference visibility, and operational fidelity. In this perspective, we examine key strategies for achieving low-loss phase modulation in integrated photonic platforms. Recent advances are systematically categorized into thermo-optic, mechanical-optic, magneto-optic, and electro-optic approaches. We discuss the underlying physical mechanisms and performance trade-offs, and the advantages and limitations of each strategy in the context of quantum photonic applications. Finally, we outline future directions and emerging approaches for developing optical modulators tailored for large-scale, programmable quantum photonic systems.