MadQCI — Madrid Quantum Communications Infrastructure

MadQCI — Madrid Quantum Communications Infrastructure

The largest QKD testbed in Europe and the longest continuously operating one: nine nodes spread across the Madrid metropolitan area, with 28 QKD modules and SDN orchestration on production Telefónica fibre. The defining feature is heterogeneity — QKD devices from multiple vendors interoperate through a common SDN / ETSI-aligned key-management layer.

Operator
Universidad Politécnica de Madrid (lead) · Telefónica (fibre) · Huawei · IMDEA Networks · multi-vendor QKD partners
Location
Madrid metropolitan area, Spain
Year
Pilot from 2018; current MadQCI architecture documented 2021; npj QI paper 2024; MadQuantum-CM expansion funded 2024–2025
Technology
Heterogeneous prepare-and-measure QKD over production fibre, co-existing with classical traffic; SDN orchestration; ETSI-aligned key delivery
Scale
9 nodes, 28 QKD modules across the metro area
Status
Operational testbed running on production telco fibre
Commercial model
Telco-led research consortium, regional government funded (Madrid CM €17 M MadQuantum-CM extension in 2024)

What it is

MadQCI runs prepare-and-measure QKD across nine nodes interconnected by Telefónica's production fibre — the same fibre that carries commercial telecoms traffic. The architecture is software-defined: all-optical switches let the SDN controller establish quantum links on demand, and the key-management plane follows ETSI QKD-network interfaces so that QKD devices from different vendors can plug into the same fabric. Martin et al. 2024 Three years of continuous operation by the time the npj QI paper was published made it the most complex, largest, and longest-running QKD testbed in Europe by the authors' definition.

Verified claims

  • 9 nodes, 28 QKD modules on Madrid metro fibre. Martin et al. 2024
  • SDN-orchestrated; multi-vendor QKD interoperation. The principal architectural contribution. Martin et al. 2024
  • Co-existence with classical traffic on production telco fibre. The testbed shares fibre with Telefónica's commercial services. Martin et al. 2024
  • Three years of continuous operation at the time of the 2024 paper. Martin et al. 2024
  • 2024–2025 expansion funded under MadQuantum-CM. The Regional Government of Madrid announced ~€16–17 M to extend the network and broaden the user base.

Things to note

  • Scope is QKD, not entanglement distribution. The protocols run on the testbed are prepare-and-measure key distribution; the architectural contribution is the multi-vendor SDN-managed fabric.
  • "Largest in Europe" refers to node count and operational lifetime on production fibre. Other deployments (e.g. OpenQKD across multiple countries) cover more territory at the project level, with shorter sustained per-site operation.
  • The vendor mix has evolved over time. Earlier MadQCI press lists Huawei as a primary partner; the current mix reflects EU funding and procurement frameworks. The 2024 paper documents the configuration running at submission.
  • Classical fibre co-existence is an engineering result. The optical noise floor on a shared dense-WDM fibre sets the operating constraint that MadQCI's per-node engineering addresses.