High-Performance Heterodyne Receiver for Quantum Information Processing in a Laser Written Integrated Photonic Platform

TL;DR

This paper presents a novel femtosecond laser micromachined integrated photonic platform on borosilicate glass for high-performance quantum information processing, demonstrating secure quantum key distribution and random number generation with high rates.

Contribution

Introduces a femtosecond laser micromachined integrated photonic circuit platform for quantum communication, enabling low-loss, polarization-insensitive, and high-rejection coherent detection.

Findings

Achieved secure CV-QRNG rate of 42.74 Gbps.

Demonstrated CV-QKD with secret key rate of 3.2 Mbit/s.

Low insertion loss and high polarization insensitivity.

Abstract

Continuous-Variable Quantum Key Distribution (CV-QKD) and Quantum Random Number Generation (CV-QRNG) are critical technologies for secure communication and high-speed randomness generation, exploiting shot-noise-limited coherent detection for their operation. Integrated photonic solutions are key to advancing these protocols, as they enable compact, scalable, and efficient system implementations. In this work, we introduce Femtosecond Laser Micromachining (FLM) on borosilicate glass as a novel platform for producing Photonic Integrated Circuits (PICs) realizing coherent detection suitable for quantum information processing. We exploit the specific features of FLM to produce a PIC designed for CV-QKD and CV-QRNG applications. The PIC features fully adjustable optical components that achieve precise calibration and reliable operation under protocol-defined conditions. The device exhibits low insertion losses ($\leq 1.28$ dB), polarization-insensitive operation, and a Common-Mode Rejection Ratio (CMRR) exceeding 73 dB. These characteristics allowed the experimental realization of a source-device-independent CV-QRNG with a secure generation rate of 42.74 Gbps and a QPSK-based CV-QKD system achieving a secret key rate of 3.2 Mbit/s. Our results highlight the potential of FLM technology as an integrated photonic platform, paving the way for scalable and high-performing quantum communication systems.