The scaling barriers currently faced by both quantum networking and quantum computing technologies ultimately amount to the same core challenge of distributing high-quality entanglement at scale. In this Perspective, a novel quantum information-processing architecture based on optically active spins in silicon is proposed that offers a combined single technological platform for scalable fault-tolerant quantum computing and networking. The architecture is optimized for overall entanglement distribution and leverages color-center spins in silicon (T centers) for their manufacturability, photonic interface, and high-fidelity information-processing properties. Silicon nanophotonic optical circuits allow for photonic links between T centers, which are networked via telecom-band optical photons in a highly connected graph. This high connectivity unlocks the use of low-overhead quantum error-correcting codes, significantly accelerating the time line for modular scalable fault-tolerant quantum repeaters and quantum processors. Published by the American Physical Society 2024
The scaling barriers currently faced by both quantum networking and quantum computing technologies ultimately amount to the same core challenge of distributing high-quality entanglement at scale. In this Perspective, a novel quantum information-processing architecture based on optically active spins in silicon is proposed that offers a combined single technological platform for scalable fault-tolerant quantum computing and networking. The architecture is optimized for overall entanglement distribution and leverages color-center spins in silicon (T centers) for their manufacturability, photonic interface, and high-fidelity information-processing properties. Silicon nanophotonic optical circuits allow for photonic links between T centers, which are networked via telecom-band optical photons in a highly connected graph. This high connectivity unlocks the use of low-overhead quantum error-correcting codes, significantly accelerating the time line for modular scalable fault-tolerant quantum repeaters and quantum processors. Published by the American Physical Society 2024
The scaling barriers currently faced by both quantum networking and quantum computing technologies ultimately amount to the same core challenge of distributing high-quality entanglement at scale. In this Perspective, a novel quantum information processing architecture based on optically active spins in silicon is proposed that offers a combined single technological platform for scalable fault-tolerant quantum computing and networking. The architecture is optimized for overall entanglement distribution and leverages colour centre spins in silicon (T centres) for their manufacturability, photonic interface, and high fidelity information processing properties. Silicon nanophotonic optical circuits allow for photonic links between T centres, which are networked via telecom-band optical photons in a highly-connected graph. This high connectivity unlocks the use of low-overhead quantum error correction codes, significantly accelerating the timeline for modular, scalable fault-tolerant quantum repeaters and quantum processors.
Single photons enable the distribution of quantum information over large distances and thus play a major role in quantum technologies such as communication and computing. Solid-state emitters are practical and efficient sources of single photons that can be manufactured in large numbers. When combined with a spin, the resulting spin-photon interfaces can store quantum states for extended periods and serve as the basis for quantum networks and repeaters. Among the many host materials explored over the past few decades, silicon stands out for its advanced nanofabrication, the maturity of its integrated photonics and microelectronics, and its high isotopic purity, which leads to exceptionally long spin coherence. These properties position silicon single-photon emitters and spin-photon interfaces among the most promising hardware platforms for implementing quantum networks and distributed quantum information processors. This review summarizes the current state of the art and open challenges towards coherent single-photon sources and scalable spin-photon interfaces based on color centers and erbium dopants in nanophotonic silicon structures.
General purpose quantum computers will utilize millions of physical qubits, thus requiring an underlying qubit technology that can be manufactured at scale. Integrated silicon photonics is an intrinsically scalable and manufacturable platform where all necessary gates are available to manipulate qubits, encoded in photons, with very high fidelity and low noise. In this talk, we will discuss architectures for fault-tolerant quantum computing with photonics in the newly-introduced fusion-based quantum computing paradigm. Fusion-based quantum computing presents a new framework for fault-tolerant quantum computation, focused on the efficient integration of quantum error correction and physical-level hardware operations. Its primitives, small entangled resource states and projective entangling gates, make it particularly useful in an integrated photonics platform, offering significant architectural simplifications and reducing requirements on physical level operations.
Color centers in wide bandgap semiconductors are prominent candidates for solid-state quantum technologies due to their attractive properties including optical interfacing, long coherence times, and spin–photon and spin–spin entanglement, as well as the potential for scalability. Silicon carbide color centers integrated into photonic devices span a wide range of applications in quantum information processing in a material platform with quantum-grade wafer availability and advanced processing capabilities. Recent progress in emitter generation and characterization, nanofabrication, device design, and quantum optical studies has amplified the scientific interest in this platform. We provide a conceptual and quantitative analysis of the role of silicon carbide integrated photonics in three key application areas: quantum networking, simulation, and computing.
Solid-state quantum light sources offer a scalable pathway for interfacing stationary spin qubits with flying photonic qubits, forming the backbone of future quantum networks. Telecom-band spin-photonic qubits, operating in the 1260-1675 nm wavelength range, are particularly well-suited for long-distance quantum communication due to minimal loss in standard optical fibers. Achieving scalability, however, hinges on fulfilling several stringent criteria: coherent spin-state control, deterministic and indistinguishable single-photon emission, and integration with nanophotonic structures that enhance radiative properties, such as lifetime, coherence, and photon indistinguishability. This study explores the state-of-the-art spin-photonic qubits across solid-state platforms, including diamond color centers, silicon carbide defect centers, quantum dots, and two-dimensional materials. Special attention is given to silicon-based emitters, particularly G, T, C- and Ci-centers, which promise monolithic integration with complementary metal-oxide-semiconductor (CMOS) technology and telecom-band operation. We classify these systems based on spin-photon interface availability, CMOS process compatibility, and emitter scalability. We also discuss recent advances in cavity quantum electrodynamics (cQED), including Purcell enhancement and quality factor engineering in integrated photonic (circuits) environments. The work highlights emerging demonstrations of quantum networking over metropolitan scales and outlines the trajectory toward chip-scale quantum photonic integrated circuits (QPICs). It combines deterministic emitter creation, coherent spin manipulation, and quantum information processing. These developments pave the way for global quantum networks, enabling secure communication, distributed quantum computing, and quantum-enhanced sensing.
We introduce an adaptable and modular hybrid architecture designed for fault-tolerant quantum computing. It combines quantum emitters and linear-optical entangling gates to leverage the strength of both matter-based and photonic-based approaches. A key feature of the architecture is its practicality, grounded in the utilisation of experimentally proven optical components. Our framework enables the execution of any quantum error correcting code, but in particular maintains scalability for low-density parity check codes by exploiting built-in non-local connectivity through distant optical links. To gauge its efficiency, we evaluated the architecture using a physically motivated error model. It exhibits loss tolerance comparable to existing all-photonic architecture but without the need for intricate linear-optical resource-state-generation modules that conventionally rely on resource-intensive multiplexing. The versatility of the architecture also offers uncharted avenues for further advancing performance standards.