Allegro Project Milestone: Advancing Entanglement Distribution for Quantum Networks

We’re excited to share a major step forward in the Allegro project!

To enable entanglement distribution, we’ve deployed a broadband Spontaneous Parametric Down-Conversion (SPDC) source, centered at 1550.12 nm. This entangled photon source connects to our quantum Reconfigurable Optical Add-Drop Multiplexer (q-ROADM), where a DEMUX separates the spectrum into multiple 100 GHz spaced channels.

Our innovative wavelength assignment scheme supports both: 🔷 Prepare-and-measure QKD links
Entanglement-based links

These logical connections are visualized in the graph shown in Fig. 1C.

At the user end, Polarisation Analysis Modules (PAMs) are employed, performing random basis measurements in either:

  • HV basis (short path) or
  • DA basis (long path).

🕒 All measurements are time-stamped and correlated using a time-digital converter, ensuring precise entanglement verification and key generation.

This architecture is a foundational step towards scalable, high-rate quantum communication networks across metropolitan-scale environments. 💡🌐

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