Crosstalk Analysis in Quantum Networks: Detection and Localization Insights with photon counting OTDR

• DOI: 10.48550/arxiv.2502.14623
• Publication Date: 2025-02-20
• Authors: Anouar Rahmouni; Prarthana Shrestha; Ya-Shian Li-Baboud; Anne Marie Richards; Yicheng Shi; Mheni Merzouki; Lijun Ma; A.B. Migdal; Abdella Battou; Oliver Slattery; Thomas Gerrits
• Keywords: Crosstalk; Optical time-domain reflectometer; Photon Counting

Optical crosstalk from sub-milliwatt classical-channel power into quantum channels presents a significant challenge in network development, introducing substantial noise that limits the network's performance, scalability, and fidelity. Here we report first demonstration using photon counting optical time-domain reflectometry ({\nu}-OTDR) to precisely identify localize between separate within same fiber fibers. The coexistence of classical signals necessitates use switches for efficient routing control. Crosstalk characterization an switch reveals depends strongly on cross connect configuration, with higher levels observed when connections are presumed be physically closer lower further apart. Additionally, found exhibits pronounced wavelength dependence, increasing over tenfold at longer wavelengths. These findings demonstrate value {\nu}-OTDR diagnosing mitigating networks. They highlight importance optimizing configurations management minimize noise, ultimately enhancing fidelity, overall performance This work establishes foundational approach addressing crosstalk, paving way more robust designs.