Quantum at Scale: Photonic’s Path to Networked Quantum Computing
Scalability remains a significant challenge for quantum computing, as current technologies have fundamental limitations for the number of qubits that can fit within a single module (a quantum chip contained in a cryostat). This raises a question: how to extend or scale beyond the qubit capacity of a single module?
Photonic, a company based in British Columbia, Canada, is tackling this challenge by advancing large-scale, distributed, and fault-tolerant quantum computing systems. Their approach integrates quantum computing and networking to address the issue of scalability.
Photonic is developing a powerful quantum computing system by combining two key technologies: silicon spin qubits and photons. Spin qubits are excellent for storing and processing information, while photons – particles of light – can travel long distances through fiber cables or satellite links to connect remote computers.
By integrating these technologies, Photonic aims to build a resource-efficient, error-corrected, and truly scalable quantum computing platform, all while using familiar silicon technology. This advancement will help reach the next chapter of quantum computing.
Phases of Quantum Computing
In their recent scientific paper, Distributed Quantum Computing in Silicon, Photonic outlines a roadmap for the development of quantum technology, highlighting three key phases on the path to commercial applications. A visual representation of these phases is provided below.
Phase 1: Quantum computers in this stage consist of single modules with a small number of physical qubits. These qubits remain too noisy for effective quantum error correction.
Phase 2: In this phase, quantum computers are still limited to single modules. However, these modules now contain enough physical qubits with low noise to form logical qubits. The industry has entered Phase 2, as indicated by multiple demonstrations of logical qubits across various platforms at increasingly large scales. The current emphasis has been on improving the performance and capacity of logical qubits within these individual modules, rather than focusing on the ability to network multiple modules.
Phase 3: The next phase of quantum computing involves growing quantum computers beyond a single module, enabling the implementation of large-scale, fault-tolerant quantum algorithms. This is what Photonic is focused on advancing.
John Dunn, Manager of Hardware Systems at Photonic, comments on the evolving focus of the quantum computing industry: “We’re starting to see a shift in perspective from the prevailing component-primary focus to a broader, systems-level perspective. We see the field moving in the direction of large-scale, distributed, fault-tolerant systems. In our view, these systems will require the seamless integration of quantum computing with quantum networking.”
Harnessing Distributed Entanglement for Scalability
Photonic’s quantum computing architecture is designed to enable limitless horizontal scalability (Phase 3 quantum computing). This means expanding the system’s capacity by adding more modules rather than upgrading the existing ones. This approach is similar to cloud computing, where additional resources can be added to manage larger workloads without changing the core system.
In classical supercomputing, expanding the system is fairly simple: you connect new modules using transceivers that enable communication between them. Quantum computing, however, is different. It relies on entanglement—a phenomenon unique to quantum mechanics where particles become interconnected.
Entanglement links qubits so that the state of one qubit instantly affects the state of another, regardless of distance. Entanglement and quantum superposition are the key building blocks of quantum parallelism, which allows quantum computers to evaluate multiple calculations at once. Unlike classical computers, which handle each bit separately, quantum computers can manipulate many qubits simultaneously in a single operation. This capability greatly increases computational power and enables complex quantum protocols and algorithms that are not possible with classical systems.
Photonic’s work is focused on optimizing for entanglement distribution – entangling two qubits over long distances, over a larger network. Instead of having only two entangled particles, multiple entangled pairs can be distributed across various locations to interact with each other. This opens a new way to connect and compute – enabling more advanced and scalable quantum technologies.
To achieve distributed entanglement, Photonic uses silicon color centers, specifically T-centers. As described in their scientific paper, T-centers are among the few color centers capable of remote entanglement. Since T-centers emit photons in the telecommunications band – the range of frequencies used for telecommunications – they enable entanglement over distances of tens or even hundreds of kilometers without the need for frequency conversion.
In Photonic’s architecture, entangled qubits are embedded in silicon photonic chips, each capable of hosting and controlling thousands of qubits. These chips are housed in separate cryostats connected by optical fiber.
Kevin Morse, Senior Technical Product Manager at Photonic, explains the complexity of deploying such a large number of qubits: “Deploying an extensive number of qubits necessitates a similarly extensive array of electrical and optical interconnects. Developing these interconnects is one challenge for the quantum computing infrastructure at Photonic. Bluefors’ high-density coaxial line solutions have been essential in addressing this challenge.”
Reliable Cooling: The Bluefors Key to Quantum Success
For Photonic’s qubits to function reliably, maintaining cryogenic temperatures is crucial. It is here that Bluefors plays a key role by providing the precise and dependable cooling required, with the XLDHe High Power Systems.
John Dunn highlights the importance of reliable cooling: “Qubits require a stable, low-temperature environment for stable operation, which is essential for reliable quantum computing. The high-power XLDHehp systems provided by Bluefors have been instrumental in maintaining these ultra-low temperatures. Precision and reliability in cryogenic solutions are of the utmost importance, and Bluefors has delivered.”
With a reliable cooling platform, Photonic can push technological boundaries even further. Kevin Morse elaborates on Photonic’s progress: “The large sample space and high cooling power of the XLDHehp system have allowed us to advance our I/O and packaging solutions, enabling us to deploy more qubits within a single system than previously possible.”
John Dunn also notes the success of the collaboration between Bluefors and Photonic: “The collaboration between Bluefors and Photonic has been a partnership focused on innovation, with Bluefors providing the cryogenic infrastructure and Photonic pushing the boundaries of quantum computing.”
Looking ahead, John also sees potential for expanding the collaboration to make new breakthroughs: “Photonic would like to see the collaboration with Bluefors evolve to include joint development of more advanced, tailored solutions. Bringing together expertise from both sides can provide fertile ground for continued innovation.”
David Gunnarsson, Chief Technology Officer at Bluefors comments: “We are eager to listen to our customers, to hear their needs, and develop our cryogenic measurement systems to match them. Our mission is to make cryogenics the solution that enables companies like Photonic to develop large-scale, fault-tolerant quantum computing systems.”
A Path to Actualizing the True Value of Quantum Computing
Photonic is at the forefront of making quantum computing a practical reality by addressing key challenges like scalability and entanglement distribution. By integrating quantum computing with quantum networking and focusing on distributed entanglement, Photonic is paving the way for significant breakthroughs in the field.
John Dunn emphasizes the scale of the task: “We know that huge amounts of quantum resources are required for the real value of quantum computing to be actualized. But we’re developing the architecture to get us there. At Photonic, we are dedicated to reaching the technical milestones necessary to make it a reality.”
With a forward-looking approach, Photonic is committed to bridging the gap between current technology and the potential of quantum computing. As John Dunn notes, “We think the future of quantum is exciting. We know that leveraging critical relationships in the quantum ecosystem – such as our relationship with Bluefors – is imperative to advancing the industry as a whole.”
Find out more about the XLDHe High Power system and discover the many applications of Bluefors technology in quantum technology.