Quantum wavelength choice improves fiber networks with classical data
Practical wavelength selection for quantum-augmented networks over shared optical fiber
Cryptography and SecurityNetworking and Internet Architecture
Summary
Optical fibers often carry both regular internet data and quantum information, but sharing the same fiber can cause problems for the fragile quantum signals. The authors study how picking the right wavelength for quantum signals can help keep their quality high while still allowing classical data to flow. They analyze conditions where quantum error correction codes work best depending on wavelength and fiber length, finding trade-offs between fidelity and the amount of usable quantum information. Their work helps define when and how quantum and classical data can share fiber without losing quantum advantages.
What this means in practice
- •For network engineers: Optimize optical fiber networks carrying both quantum and classical signals by selecting wavelengths that maximize quantum fidelity and throughput.
- •For telecommunications operators: Plan deployment of quantum-augmented fiber links using wavelength strategies to ensure certified quantum performance alongside existing data rates.
Authors
Nitin Jha, Prateek Paudel, Abhishek Parakh
Abstract
In a quantum augmented network, sharing optical fiber with classical traffic requires quantum wavelength selection to balance logical fidelity, block acceptance, and classical data reception. Here we develop a wavelength-selection framework for an error-corrected three-stage quantum communication protocol. Under a thermal-background model with independent errors, an ideal one-photon receiver, and ideal recovery, we derive an accepted qubit channel and a key-independent lower bound on logical entanglement fidelity. Combining this bound with block acceptance gives an entanglement-fidelity yield bound, which we maximize over evaluated wavelengths subject to fidelity and classical link-budget requirements. For the Steane [[7,1,3]] code at 5 km per traversal and -10 dBm per classical channel, the largest fidelity certificate occurs near 1537 nm, whereas the largest yield bound occurs near 1551 nm. Along the 1.25 Gb/s classical link budget with 0.2% base error, the optimized yield bound falls below 10^-6 near 10 km per traversal, while fidelity remains certified at 0.99 or higher at longer spans. These results distinguish fidelity and yield constraints and identify certified operating regions for quantum-augmented networks sharing optical fiber.