Cisco Systems and Qunnect said they have built and operated a functioning quantum network spanning Brooklyn and Manhattan in New York that transmits quantum signals over standard fiber optic cables, achieving performance on par with laboratory experiments.
The demonstration combined Qunnect’s hardware, produced in Brooklyn, with software from Cisco to tackle a series of practical issues that arise when deploying quantum systems in existing data centers and city environments. According to the companies, the trial validated methods to keep fragile quantum links stable across live infrastructure.
Quantum computers exploit principles of quantum physics to complete calculations that would otherwise take conventional machines thousands of years, but they typically need bulky cryogenic cooling systems. Qunnect’s chief executive, Noel Goddard, said the company’s approach confines cryogenic cooling to a single central hub while allowing other data centers connected to that hub to use equipment that operates at room temperature.
The partners noted that quantum hardware and networks are highly sensitive to external disturbances such as vibration. A coauthored research paper by Cisco and Qunnect highlighted a particular element of the startup’s kit - devices described as automatic polarization controllers - as a key enabler in maintaining the integrity of the quantum link over a 17.6-kilometer (10.9-mile) stretch of fiber optic cable.
"It corrects for real-world problems," Goddard said, adding that data center cabling often stretches for tens of kilometers and passes through a variety of patch panels and connections that can resemble "a rat’s nest." The implication is that polarization drift and other real-world disturbances can be compensated for without recreating ideal lab conditions in every location.
Ramana Kompella, vice president and head of Cisco Research, described the experiment as "foundational" to Cisco’s longer-term objective of linking quantum computers within individual data centers and eventually interconnecting quantum-capable data centers into a broader quantum internet.
In the nearer term, Kompella said practical quantum networks could find uses in areas such as stock trading. He noted that a quantum technique called "teleportation" can permit physically separated computers to share information effectively instantaneously, rather than taking a few milliseconds for signals to propagate at the speed of light. "Trading computers that are tens of kilometers away, and they want to make a coordinated decision or a stock sell or a buy, without hitting the speed of light limitations you typically have. Quantum entanglement networks can actually really help," Kompella said.
Summary
Cisco and Qunnect ran a 17.6-kilometer quantum communications trial between Brooklyn and Manhattan, using Qunnect hardware and Cisco software to address vibration sensitivity and polarization drift on standard fiber optic cables. The setup isolates cryogenic cooling to a central hub while enabling remote data centers to use room-temperature equipment, and the partners highlighted potential short-term applications in trading.
Key points
- The trial spanned 17.6 kilometers of real-world fiber optic cable between Brooklyn and Manhattan.
- Qunnect supplied hardware that allows cryogenic cooling at one central hub, with other connected sites operating at room temperature.
- Automatic polarization controllers were reported to maintain network integrity across existing data center cabling.
- Sectors impacted include data center infrastructure, networking equipment providers, and financial trading systems that could leverage latency advantages.
Risks and uncertainties
- Sensitivity to external vibration and other environmental disturbances remains a fundamental challenge for quantum links; while the demonstration addressed polarization drift, broader operational resilience in diverse conditions remains to be established - relevant to data center operators and network providers.
- The complexity of existing cabling, patch panels and heterogeneous infrastructure in data centers poses deployment and maintenance challenges that could affect scalability - a concern for companies managing large-scale fiber networks.
- Near-term practical applications cited, such as trading use cases, are presented as possibilities; any economic or market impact will depend on further engineering, integration, and validation across production environments.