Designing Noise-Robust Quantum Networks Coexisting in the Classical Fiber Infrastructure

TL;DR

This paper explores how to enable quantum and classical communications to coexist in shared fiber infrastructure by analyzing noise, wavelength optimization, and entangled photon performance over long distances.

Contribution

It provides a detailed characterization of quantum-classical coexistence in fiber optics, identifying optimal wavelength combinations and noise mitigation strategies.

Findings

Certain wavelength combinations significantly reduce Raman noise.

Record C-band power (>18 dBm) used in experiments.

Quantum entanglement performance maintained over 48 km fiber.

Abstract

The scalability of quantum networking will benefit from quantum and classical communications coexisting in shared fibers, the main challenge being spontaneous Raman scattering noise. We investigate the coexistence of multi-channel O-band quantum and C-band classical communications. We characterize multiple narrowband entangled photon pair channels across 1282 nm-1318 nm co-propagating over 48 km installed standard fiber with record C-band power (>18 dBm) and demonstrate that some quantum-classical wavelength combinations significantly outperform others. We analyze the Raman noise spectrum, optimal wavelength engineering, multi-photon pair emission in entangled photon-classical coexistence, and evaluate the implications for future quantum applications.