Quantum integrated squeezed light enhancement and detection with photonics integrated circuits: a single-pass configuration

We introduce the concept and proof-of-principle design of a new type of high-speed photonic integrated analyzers for continuous-variable quantum states. These analyzers aim to address both unconditionally entangled states and noise-squeezed states. Unlike current squeezed state analyzers and entangled state analyzers, our devices do not rely on optical phase-locked loops. Instead, they use a phase-diversity architecture where the local oscillator operates as a free-running laser. This method greatly simplifies system design and allows for photonic integrated circuit realizations that meet the strict size, weight, and power requirements of space-based quantum communication systems. We explain how the integrated analyzers for unconditionally entangled states and noise-squeezed states work, outline their methods for characterizing entanglement and squeezing in the digital domain, and provide a tolerance analysis of the essential photonic components. Numerical modeling shows that our design achieves over 10dB parametric gain with sub-10mW pump powers. It also allows for squeezing levels that exceed the 8dB threshold needed for fault-tolerant continuous-variable quantum computing. This work offers a route to scalable, practical photonic analyzers for quantum communication and information processing applications.