Live ‘quantum network’ being tested in New York – overcoming key hurdles could bring us closer to an ‘unhackable’ internet – Image for illustrative purposes only (Image credits: Pixabay)
New York – Researchers have conducted a live test of a quantum network connecting three locations across the city using existing fiber-optic infrastructure. The demonstration, involving entangled photons, marks progress toward a future internet that could resist hacking attempts through fundamental laws of physics. This effort involved collaboration between academic and industry partners working to move quantum communication out of controlled laboratories and into real urban environments.
The Setup Behind the Citywide Test
A team from New York University partnered with the quantum startup Qunnect and networking company Cisco to link nodes in Brooklyn and Manhattan. Entangled photon pairs originated at a facility in Brooklyn and traveled several miles through commercial fiber cables to a central hub in Lower Manhattan. A third node at the hub performed entanglement swapping, allowing the system to distribute quantum correlations across the network on demand. This hub-and-spoke design centralized sensitive equipment while connecting the outer points. The test covered distances of roughly five to six miles per segment over active telecom lines. Such a configuration demonstrated that quantum signals could operate alongside conventional data traffic without dedicated new infrastructure.
Key Technical Achievements in Real Conditions
The experiment succeeded in entanglement swapping, a process that links photons that never directly interacted. Cryogenic detectors at the hub measured the arriving photons and transferred the entanglement state, creating effective connections across the full network. Polarization fidelity remained high despite environmental factors such as temperature changes and vibrations common in dense urban settings. Photon loss in fiber cables presented a major obstacle, yet the short metropolitan distances allowed measurable success rates. The system achieved entanglement distribution rates suitable for initial applications while managing noise that would otherwise destroy fragile quantum states. These results showed that existing city infrastructure can support quantum links without immediate need for entirely new cabling.
Implications for Secure Communications
Quantum principles make interception detectable because any measurement disturbs the particle states. This property underpins device-independent quantum key distribution, which could generate encryption keys immune to undetected eavesdropping. Financial institutions, government agencies, and healthcare providers stand to benefit first from such secure key sharing. Longer-term possibilities include networks that support distributed quantum computing. Complex problems in drug discovery or climate modeling could draw on combined processing power across multiple sites. Quantum sensing applications, such as precise timing or navigation independent of satellite systems, also become more feasible with reliable entanglement distribution.
- Successful multi-node entanglement over live commercial fiber
- Hub-and-spoke architecture reduces equipment costs at each location
- Real-world noise and loss managed within metropolitan scale
Obstacles That Still Require Solutions
Photon absorption in fiber limits reliable transmission to shorter distances without amplification. Beyond roughly 60 miles, entanglement rates drop sharply, and current technology lacks the quantum memories needed for repeaters that could extend range. The New York test remained within compact city limits where density of users and infrastructure offers practical advantages. Further development must address scalability while preserving the security guarantees of quantum protocols. Continued experiments will determine how quickly these systems can expand beyond initial metropolitan testbeds. The work provides a concrete blueprint for incremental progress rather than an immediate nationwide solution.