Canadian researchers, in collaboration with international partners, have successfully demonstrated metropolitan-scale quantum teleportation and entanglement distribution over fiber-optic networks. These experiments, conducted largely over deployed urban fiber infrastructure in Calgary, mark a critical step toward practical quantum communication systems. These achievements position Canada among the leading nations advancing the "quantum internet" for secure communications by maintaining high-fidelity quantum states over tens of kilometers of active telecommunications fiber.
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Can Quantum Coms Coexist with Fiber-Optics?
Quantum entanglement describes a phenomenon where two particles (such as photons) become correlated such that measuring one instantaneously affects the state of the other, regardless of separation distance. This property enables Quantum Key Distribution (QKD), a method of encryption fundamentally secure against eavesdropping. Unlike effective classical encryption, which relies on mathematical complexity, quantum encryption relies on the laws of physics: any attempt to intercept the signal disturbs the entangled state, alerting the users to the breach.
Global efforts in quantum networking are accelerating. China’s Micius satellite demonstrated space-to-ground quantum links in 2017, and the U.S. Department of Energy has outlined a blueprint for a national quantum internet. Canada’s contribution is distinct because of its focus on coexistence: demonstrating that quantum networks can operate over the same fiber-optic cables already buried under cities, rather than requiring expensive, dedicated "dark fiber" lines.1
The urgency for this technology stems from the "harvest now, decrypt later" threat. Adversaries are currently harvesting encrypted data with the intention of decrypting it once sufficiently powerful quantum computers emerge. Organizations handling sensitive long-term data, financial institutions, healthcare providers, and government agencies, require quantum-safe solutions immediately.
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Key Findings & Technical Achievements
The central achievement of the Canadian pilot programs, led by researchers at the University of Calgary and partners at Caltech and Fermilab, was the successful teleportation of quantum states across a metropolitan network. In key experiments, researchers achieved entanglement fidelities exceeding 90% over a 44-kilometer loop of deployed fiber.2
Stability in Urban Environments
A major technical hurdle for quantum networks is environmental noise. Changes in temperature, subway vibrations, and physical stress on fiber cables usually scramble the "phase" of quantum states. The Canadian tests utilized time-bin qubit encoding, a technique that makes the quantum information significantly more robust against these environmental fluctuations compared to traditional polarization encoding. This allowed the system to run autonomously for extended periods with high fidelity.2
Silicon Photonic Integration
Scaling these networks requires moving away from bulky optical tables to compact chips. Recent advancements in silicon photonics, conducted by partners in the UK and Canada, have demonstrated chip-to-chip quantum teleportation. These silicon devices can generate and manipulate entangled photons on a micro-scale, a prerequisite for mass-manufacturing quantum transceivers that can be installed in standard server racks.3
Network Coexistence
Perhaps most relevant to industry, researchers are validating that quantum signals can coexist with classical internet traffic. By using precise timing synchronization and wavelength division multiplexing (WDM), "dim" quantum pulses can be transmitted alongside "bright" classical data lasers. This validates the economic feasibility of upgrading current telecom infrastructure rather than replacing it entirely.4
Methodology and Infrastructure
The experiments were conducted using standard single-mode telecommunications fiber- same type of cable that carries residential internet.
The Setup: The network topology typically involves three nodes: Alice, Bob, and Charlie. In the Calgary tests, the central node (Charlie) was located in a generic telecommunications facility, while Alice and Bob were situated in distinct locations (e.g., a university lab and a downtown office).
The Process: Entangled photon pairs are generated at the central node and sent through the fiber to the end users. When Alice performs a specific measurement on her photon, the state is "teleported" to Bob’s photon, contingent on the entanglement link.
Synchronization: To ensure the photons from different locations arrive at the central hub at the exact same instant (a requirement for quantum interference), the team used off-the-shelf equipment and proprietary feedback systems to stabilize the photon arrival times to within picoseconds.2
Commercial and Policy Implications
These technical successes directly support Canada’s National Quantum Strategy, a federal initiative backed by $360 million in funding to solidify Canada’s leadership in quantum science.5
Industry early adopters span several key sectors. In finance, the banking industry stands out as the primary commercial focus, where quantum-secured links can safeguard high-value inter-bank transfers and settlement data. Critical infrastructure providers, including utilities and defense networks, are also evaluating these systems to secure command-and-control grids from cyber-physical threats. Meanwhile, telecommunications companies see the potential for a new service tier; for example, Telus and Bell may eventually offer “Quantum-Secured Bandwidth” as a premium enterprise product.
Public-private partnerships are helping to speed up this shift. In Toronto, Xanadu is scaling quantum computing hardware, while firms like Anyon Systems are working on vertically integrating quantum components. The ability to integrate these technologies into existing fiber networks, validated by recent university-led trials, represents the “missing link” to making commercial deployment viable.
Challenges and Limitations
Despite successful demonstrations, several major engineering challenges still need to be addressed before a national quantum internet becomes a reality. One key hurdle is distance: photon loss in optical fiber limits direct transmission to about 100 kilometers. Extending the network over longer distances (say, from Toronto to Montreal) requires quantum repeaters. These devices are designed to catch, store, and re-transmit entangled photons, but they remain experimental and currently struggle with low efficiency and short memory lifespans.
Another challenge involves rate limitations. Quantum teleportation rates over real-world fiber are still quite low, typically in the range of hertz to kilohertz. While this is adequate for secure key exchange via quantum key distribution (QKD), it's far too slow to support distributed quantum cloud computing.
Finally, the lack of standardization is a pressing issue. There’s no universally accepted protocol for quantum networking, which makes interoperability difficult. For instance, a quantum memory system in Calgary may not seamlessly interface with a photon source in Ottawa, especially when different vendors are involved.
Future Developments
The roadmap for Canadian quantum networking is unfolding in three distinct phases. The first focuses on metropolitan expansion, which means scaling up existing testbeds in Calgary, Montreal, and Toronto by adding more network nodes and increasing key-generation rates.
Next comes the development of hybrid networks that combine terrestrial fiber with satellite links. The Canadian Space Agency is backing this effort through the Quantum Encryption and Science Satellite (QEYSSat) mission, which aims to serve as a “trusted node” in orbit, enabling secure connections between distant metropolitan networks.
Looking over a 10-year horizon or more, the vision is to build a fully entangled quantum internet. This would connect quantum computers across the country, allowing for distributed computing power far beyond the capabilities of any single supercomputer.
Though a coast-to-coast fiber link remains years away due to the need for quantum repeaters, Canada’s success in stabilizing entanglement over city-scale infrastructure proves that the foundation for the quantum internet is already in the ground.
Wondering if quantums coms are happening soon? We talk about it here
References & Further Reading
- Ren, J.-G., Xu, P., Yong, H.-L., Zhang, L., Liao, S.-K., Yin, J., Liu, W.-Y., Cai, W.-Q., Yang, M., Li, L., Yang, K.-X., Han, X., Yao, Y.-Q., Li, J., Wu, H.-Y., Wan, S., Liu, L., Liu, D.-Q., Kuang, Y.-W., ... Pan, J.-W. (2017). Ground-to-satellite quantum teleportation. Nature, 549(7670), 70–73. https://doi.org/10.1038/nature23675
- Valivarthi, R., Puigibert, M. I., Zhou, Q., Aguilar, G. H., Verma, V. B., Marsili, F., Shaw, M. D., Nam, S. W., Oblak, D., & Tittel, W. (2020). Teleportation systems toward a quantum internet. PRX Quantum, 1(2), 020317. https://doi.org/10.1103/PRXQuantum.1.020317
- Llewellyn, D., Ding, Y., Faruque, I. I., Paesani, S., Bacco, D., Santagati, R., Qian, Y.-J., Li, Y., Xiao, Y.-F., Huber, M., Malik, M., Sinclair, G. F., Zhou, X., Rottwitt, K., O'Brien, J. L., Rarity, J. G., Gong, Q., & Oxenløwe, L. K. (2020). Chip-to-chip quantum teleportation and multi-photon entanglement in silicon. Nature Physics, 16(2), 148–153. https://doi.org/10.1038/s41567-019-0727-x
- Chung, J., Eastman, E. M., Kanter, G. S., Kapoor, K., Lauk, N., Pena, C., Plunkett, R. K., Sinclair, N., Thomas, J., Valivarthi, R., Xie, S., Kettimuthu, R., Kumar, P., Spentzouris, P., & Spiropulu, M. (2022). Design and implementation of the Illinois Express Quantum metropolitan area network. IEEE Transactions on Quantum Engineering, 3, 1–20. https://doi.org/10.1109/TQE.2022.3221029
- Government of Canada. (2023). National quantum strategy. Innovation, Science and Economic Development Canada. https://ised-isde.canada.ca/site/national-quantum-strategy/en
- Bhaskar, M. K., Riedinger, R., Machielse, B., Levonian, D. S., Nguyen, C. T., Knall, E. N., Park, H., Englund, D., Loncar, M., Sukachev, D. D., & Lukin, M. D. (2020). Experimental demonstration of memory-enhanced quantum communication. Nature, 580(7801), 60–64. https://doi.org/10.1038/s41586-020-2103-5
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