Karen Sloyan

Deployable networks and regulatory feedback are creating new challenges for quantum communication research. One of the most important challenges highlighted in QKD position papers is the trusted-node concept. At city scale, this problem is already practical issue: 5–50 users may need to share secret keys in an any-to-any topology. In a conventional trusted-node architecture, the telecom operator responsible for the quantum network becomes a trusted organization for all users and all sensitive data. Three approaches can be considered to overcome this limitation: (i) equip every user with both a transmitter and a receiver and use an N × N optical switch [3]; (ii) distribute entanglement between selected user pairs; (iii) use MDI-QKD or TF-QKD with a 2 × N optical switch. In this work, we demonstrate a field deployment of time-shared entanglement distribution between users selected on demand. We consider this approach highly practical because it keeps network management simple and allows the same receiver implementation to be used for every user. Our deployment is located in the Abu Dhabi Global Market (ADGM) free zone in Abu Dhabi. It opens an opportunity for finance-sector clients to test end-user solutions on a quantum-safe network, both by using AES encryptors fed by quantum-generated keys and by applying ETSI GS QKD 014 to request keys at the application layer.

We demonstrated a configurable on-chip entangled photon source for BBM92 quantum key distribution (QKD) networks. Built on a scalable silicon-on-insulator (SOI) platform, our design incorporates tunable ring resonators. These allow precise, on-chip adjustment of the quality factor (Q-factor), which is central to optimizing the brightness and noise of the source. Our extensive characterization shows this source achieves a coincidence-to-accidental ratio (CAR) of 48239, $g^2(0)$ of $6.8\times10^{-4}$ and raw coincidence rate of 212k counts/second. This exceeds performance reported in the literature. This performance directly translates to higher secure key rates, lower QBER and QKD robustness. The ability to fine-tune source parameters provides flexibility, allowing adaptation to diverse network conditions and optimization for specific QKD applications. This research marks a step toward creating compact, efficient, and reconfigurable entangled sources for practical and scalable quantum communication.