Scalable Fault-Tolerant Quantum Technologies with Silicon Colour Centres

The article presents a vision for scalable quantum technologies, focusing on the integration of quantum computing and quantum networking. It proposes an architecture that uses silicon-based spin qubits, particularly the T centre spin-photon interface, to create a modular and horizontally scalable system. This architecture addresses the current challenges in quantum technologies, particularly the difficulties in distributing high-quality entanglement at scale, by leveraging telecom photons for photonic links and integrating quantum processors with quantum repeaters.

Key points discussed include:

1. Scalable Quantum Networking and Computing: The proposed architecture uses a high-connectivity system, where quantum repeaters and quantum processors are connected through telecom photons. This setup enables horizontal scaling, allowing for the creation of large, modular quantum networks and processors.

2. Silicon T Centres: The T centre spin-qubit system in silicon offers a strong spin-photon interface, high fidelity, long-lived spin memories, and compatibility with integrated photonics. These qualities make it ideal for building scalable quantum computing and networking systems.

3. Modular Quantum Processing: The architecture emphasizes modularity, allowing quantum processors to be linked via telecom photons. This modularity enables more efficient entanglement distribution and scaling of quantum resources.

4. Quantum Error Correction (QEC): The architecture supports low-overhead quantum error correction codes, such as Quantum Low-Density Parity-Check (QLDPC) codes, which are crucial for achieving fault tolerance at scale.

5. Quantum Networking Applications: The paper highlights the use of this architecture for several quantum networking applications, including Memory-Assisted Measurement-Device-Independent Quantum Key Distribution (MA-MDI QKD) and blind quantum computing. Both applications benefit from the high-connectivity entanglement distribution and the ability to handle photon loss and quantum errors effectively.

6. Quantum Repeaters: Quantum repeaters, which are essential for long-distance quantum communication, are integrated into the system. These repeaters use T centre processors to create and distribute entanglement over large distances, facilitating the development of a global quantum network.

In conclusion, the article presents a scalable and robust architecture for quantum networking and computing that can be implemented using silicon T centres. It leverages high-connectivity, modular systems to overcome current scaling challenges, offering a promising route to large-scale, fault-tolerant quantum technologies.