Key Highlights
- Quantum internet connects computers and devices using fiber optics, enabling secure communication and advanced computational tasks.
- Cities like Albuquerque and Chattanooga are leading the development of metro-scale quantum networks, with international efforts in Europe and Asia.
- Quantum key distribution (QKD) enhances security by detecting eavesdropping, making it a key near-term application of quantum networking.
- Hardware challenges, including high costs and size, are current barriers, but innovations like Cisco's Universal Quantum Switch aim to address these issues.
- Scaling quantum networks beyond metro areas will create a 'quantum cloud,' facilitating large-scale collaboration and problem-solving across regions.
Quantum computing, sensing, and security are linked by the need to network computers, devices, and institutions to exchange information. Fiber optics, specifically telecommunications-grade fiber and the underlying electronics, are being used as the go-to medium to build the building blocks of the quantum internet.
Service providers should recognize that quantum networking will emerge as a new metro and middle-mile opportunity in the next few years. Still, it will be uniquely different from the internet boom of the 1990s.
Albuquerque is the latest city to join the list of municipalities that have demonstrated or operate metro-scale quantum networks, including Boston, Chattanooga, Chicago, New York, San Francisco, and Washington D.C., with international efforts taking place in China, Germany, Italy, Netherlands, and the UK, to highlight a few of the many places where a mix of commercial companies, government researchers, and universities are working to unlock quantum networking and usher in a new era of information technologies.
A closer look at it is instructive. New Mexico has put in $25 million to build what its participants are calling America’s first open-access entanglement-based quantum network, serving as a testbed for startups and companies developing commercial quantum technologies. Participants in the local quantum ecosystem include Sandia National Laboratories, Los Alamos National Labs, the University of New Mexico, startups, and venture firms hoping to capitalize on quantum’s potential.
EPB has been operating its own commercial quantum network in Chattanooga since 2023, and the addition of quantum to its smart grid and broadband services is expected to add up to $10 billion of total economic impact delivered to the city by 2035 since commissioning its initial fiber network in 2010.
What’s it good for?
The world of quantum is much different than traditional digital computing. Digital computing is relatively simple because information is represented as a bit with a value of 0 or 1. In the quantum world, information is processed using the qubit as the basic unit of information and a qubit can exist in multiple states simultaneously. Because of this characteristic, multiple qubits can provide computational power that far exceeds the capability of any digital computer.
Leveraging the power of qubits in large numbers, quantum computing can tackle problems that would take traditional supercomputers thousands of hours or longer to solve, enabling scientists and engineers to tackle problems in materials science, drug discovery, optimizing supply chains and other logistical systems, and accelerating financial analysis. Quantum computing also threatens the security of existing large-factor-based encryption systems, such as RSA and ECC, with a “quantum apocalypse” that could break these schemes in the years ahead.
Putting more qubits together means networking quantum computers, which requires moving qubits around. For networking purposes, a photon can serve as a qubit to carry information. Since there’s plenty of telecom hardware that generates and transmits photons at room temperature, fiber is the perfect medium for quantum networking.
Under the rules of quantum physics, you can’t simply clone qubits without losing their superposition properties. In normal classic digital networks, you can move a photon between 50 and 100 kilometers before it needs to be amplified. In contrast, the photon can be moved from point to point using switches and routers along different paths. But classic amplification, switches, and routers all end up breaking superposition, so more specialized hardware must be built to move qubit information across multiple hops and longer distances without disrupting superposition.
The near-term application for quantum networking is for enhanced security. Quantum key distribution (QKD) uses qubits to share cryptographic keys between parties securely. Anyone who looks at a qubit in transit immediately disrupts its quantum state and alerts users to get rid of the compromised key. Current QKD solutions depend on point-to-point links and require a repeater between the two parties. Still, a quantum router would enable keys to be distributed across multiple points and over longer distances than the typical 50 to 100 kilometers of fiber before a repeater.
Making quantum network hardware
Quantum switches and routers use a property called entanglement swapping to share information held in qubits between locations and across distances. Cisco, Deutsche Telekom, and Qunnect have demonstrated entanglement in metro-grade networks using existing telco-grade fiber and commercial hardware, with the biggest hurdle to widespread adoption being the cost of hardware at about $1 million per rack.
Meanwhile, closer to the quantum computer, Cisco has announced its Universal Quantum Switch. This prototype allows you to connect quantum computers from different vendors and different types of quantum sensors onto a single network. Since there are numerous hardware approaches to building a quantum computer and probably just as many sensor approaches, the universal quantum switch allows users to connect everything without being locked into a single hardware type.
Building and scaling
As discussed earlier, various research, government, and a few commercial organizations have built metro-scale networks worldwide. Being able to conduct QKD over a quantum network to multiple parties, rather than using dedicated fibers for each key distributor and key receiver, would be a major step toward wider adoption of QKD.
Similarly, a true quantum network with quantum switches and routers will enable networking of multiple computers across a metro region, allowing users to build a “quantum cloud” that taps into clusters of quantum computers using different hardware architectures.
Initially, quantum networks will be like the early days of the internet, with government research funding and contributions from the private sector. Still, QKD and the need for improved security may drive much earlier commercial involvement and participation. Corporations with sensitive information, especially financial institutions, are always seeking the latest security enhancements. Last year, Juniper Research estimated that about 1,000 businesses had adopted QKD and expects that number to triple by 2030.
Scaling up beyond the metro will also likely follow the growth path of the internet in the 1990s, but with one key exception. One of the drivers of the internet's explosive growth during that era was the web, with organizations opening up resources to other organizations, businesses, and the public at large. Quantum internet use is likely to reside in organizations and businesses, since mass-market utilization of quantum computing and sensing has not yet emerged. Instead, corporations and research institutions will cluster quantum computers as cloud resources for solving large problems that are not practical on traditional hardware.
Keeping this in mind, building a quantum middle mile will be a substantial opportunity for fiber operators over the next few years as connectivity needs expand beyond metro distances into regional and ultimately national distances. For example, it is easy to see how a regional quantum network between New York and Washington, D.C. could develop and evolve, followed by the connection and merger of other regional networks into a larger whole until the entirety of the continental United States is connected via a single quantum network. We can expect to see other large quantum networks emerge in China, Europe, and possibly in parts of Asia.
The only thing holding back the rapid construction of quantum networks is the current state of networking hardware development. Cisco’s Universal Quantum Switch is a prototype with many features on the roadmap but not yet released, while Qunnect’s Carina quantum network device is a full rack of equipment that lists for $1 million. Hardware will have to become more affordable and smaller in size for quantum networking to move into the mainstream, but it is coming. The Fiber Broadband Association will have more information on our own quantum plans in the months ahead.
About the Author
Gary Bolton
vice president, global marketing
Gary Bolton is the president and CEO of the Fiber Broadband Association.