Stream 8: Quantum Communications
The long and potholed road to a UK quantum network
Alessandro Fedrizzi, Heriot-Watt University
Quantum computer development is rapidly progressing to a stage where it will threaten conventional cybersecurity. Post-quantum encryption algorithms are now being deployed as a lifeline, but unconditional security can only be achieved via quantum communication. In this talk I will give an overview of the UK Integrated Quantum Networks (IQN) Hub, whose goal it is to enable secure quantum networking for computing, sensing, and communication at all distant scales. I will highlight early example applications in which network advantages can be achieved through multi-user entanglement.
Resources and applications for advanced quantum networking
Eleni Diamanti, CNRS, Sorbonne University & Welinq
We discuss the main concepts, critical photonic resources, present efforts and challenges ahead aiming at the deployment of quantum communication networks at various stages of development and at a scale of data centres or global infrastructures. We present examples of applications of such networks spanning from ultrasecure communication to advanced cryptographic and communication protocols in distributed architectures. We argue that optical quantum networking, powered by entanglement as a fundamental resource and enhanced by highly efficient quantum memories, is a key for scale up of quantum technologies, pursued by rapid advancements towards industrialization and leading the path to an era of quantum connectivity.
Distributed Quantum Computing across a Trapped-Ion Quantum Network
Dougal Main, University of Oxford
Distributed quantum computing (DQC) combines the computing power of multiple networked quantum processing modules, ideally enabling the execution of large quantum circuits without compromising performance or connectivity [1]. Photonic networks are well-suited as a versatile and reconfigurable interconnect layer for DQC; remote entanglement shared between matter qubits across the network enables all-to-all connectivity via quantum gate teleportation (QGT) [2,3]. For a scalable DQC architecture, the QGT implementation must be deterministic and repeatable; until now, no demonstration has satisfied these requirements.
I will present our recent experimental demonstration of distributed quantum computing between two photonically interconnected trapped-ion modules [4]. Using heralded remote entanglement shared between two network qubits in separate modules, we deterministically teleport a controlled-Z gate between circuit qubits across the quantum network. Furthermore, we construct distributed quantum circuits compiled with multiple non-local two-qubit gates, including the SWAP gate, the iSWAP gate, and the implementation of Grover’s algorithm.
[1] J. I. Cirac, A. K. Ekert, S. F. Huelga, and C. Macchiavello, Distributed quantum computation over noisy channels. Phys. Rev. A 59, 4249 (1999).
[2] L. Jiang, J. M. Taylor, A. S. Sørensen, and M. D. Lukin, Distributed quantum computation based on small quantum registers. Phys. Rev. A 76, 062323 (2007).
[3] C. Monroe, et al. Large-scale modular quantum computer architecture with atomic memory and photonic interconnects. Phys. Rev. A 89, 022317 (2014).
[4] D. Main et al., Distributed quantum computing across an optical network link. Nature 638, 383–388 (2025).