Designing noise-robust quantum networks coexisting in the classical fiber infrastructure

Area of Science:

• Quantum communication
• Optical networking
• Photonics

Background:

• Scalable quantum networking requires integrating quantum and classical communications in shared optical fibers.
• Spontaneous Raman scattering (SRS) noise poses a significant challenge to this coexistence.
• Optimizing wavelength allocation is crucial for mitigating SRS noise and ensuring signal integrity.

Purpose of the Study:

• To investigate the coexistence of multi-channel O-band quantum and C-band classical communications in standard optical fiber.
• To characterize the impact of high-power classical channels on quantum channels.
• To identify optimal wavelength combinations for minimizing noise and maximizing quantum channel performance.

Main Methods:

• Co-propagation of narrowband entangled photon pair channels (1282 nm-1318 nm) with C-band classical communications over 48 km of installed standard fiber.
• Characterization of quantum channel performance under record C-band power levels (>18 dBm).
• Analysis of the Raman noise spectrum and multi-photon pair emission.

Main Results:

• Demonstrated significant performance differences between various quantum-classical wavelength combinations.
• Identified specific wavelength pairings that outperform others in terms of quantum channel fidelity and noise resilience.
• Quantified the impact of high-power classical channels on quantum signal-to-noise ratio.

Conclusions:

• Successful co-propagation of O-band quantum and C-band classical signals is achievable with careful wavelength management.
• Wavelength engineering is a critical factor in mitigating Raman scattering noise for future quantum networks.
• The findings provide essential insights for designing and deploying scalable, hybrid quantum-classical communication systems.