Entangled State of Mind in Lower Manhattan

By: Noel Goddard and Mehdi Namazi

Left: The team at Qunnect’s GothamQ hub in Brooklyn generated entangled photons and monitored the performance of the network. Middle: The Qunnect and NYU team at GothamQ’s NYU node, measuring the arriving stream of entangled photons from Brooklyn. Upper right: GothamQ’s fiber map currently consists of 6 and 34km long fibers through Queens and Brooklyn (looped) along with 6 and 16km long fibers between the Brooklyn and Manhattan nodes. The latter fibers were used in this demo. Lower right: A sample of the data taken during the run, demonstrating an uninterrupted operation over 12 hours with better than 99% uptime, distributing ~15,000 pairs of high quality entangled photons between Manhattan and Brooklyn. (Maps Data: Google @2022)

The quantum internet is closer than you think. In fact, if you were near New York University’s Manhattan campus a few weeks ago, there’s a chance you were walking above quantum particles flowing through fibers connected to Brooklyn’s Navy Yard under the city streets.

That’s because today we announced an industry-defining milestone, in collaboration with NYU’s Center for Quantum Information Physics (CQIP): we sent quantum information through standard telecom fiber in New York City, using Qunnect’s quantum-secure networking technology. This opens the door for customers in financial services, critical infrastructure, and telecom in the New York metropolitan area to pilot quantum technologies.

During this test, we successfully distributed and preserved entanglement between two remote, independent locations, at a rate of 15,000 pairs/second over 10 miles of real fiber, with 99% uptime and no cryogenic detectors – a breakthrough that advances the next generation of networking protocols for quantum communications. The test was conducted on Qunnect’s GothamQ, a quantum network built with commercial fiber optic cable with a node connecting to NYU’s campus in Manhattan.

We are the first company that has successfully distributed entanglement at this performance level on existing telecom infrastructure.

The team used the following Qunnect products during the demonstration:

  • QU-SOURCE injected highly pure, polarization-entangled qubits into the GothamQ fibers
  • QU-LOCK stabilized the lasers driving QU-SOURCE with atomic precision
  • QU-APC actively compensated for noise in the fiber channel, maintaining transmission fidelities of >95% with >99% uptime.

Analogous to noise-canceling headphones, the QU-APC device sampled the real-time noise in the fiber and calculated a correction signal. This enabled GothamQ to preserve the fragile entangled qubits underlying all quantum-secure protocols at unprecedented and sustainable rates, and marks the first time an active stabilization technology for quantum has been used on telecom fiber.

Why is this important?

By leveraging the laws of quantum physics to protect data, quantum communications will revolutionize cybersecurity and transform the Internet. One of the phenomena that quantum networks seek to take advantage of is entanglement, in which two particles link together no matter how far apart they are in space; products are being developed that use entanglement to extend the range of quantum networks.

Entangled qubits, or quantum bits, are notoriously delicate, and the slightest interaction with their surroundings, like temperature changes and vibrations from buried fiber, can distort them. For this test with NYU, we deployed two QU-APC instruments at our lab in Brooklyn and at NYU to preserve the high rate of entanglement.

Our work with NYU underscores the power of Qunnect’s product suite to enable quantum communications to solve real-world challenges. New York City is home to one of the world’s densest ecosystems of finance, critical infrastructure and communications infrastructure that stands to benefit from the realization of improved security. But this density presents an equally daunting number of deployment and scaling challenges. Now that we have successfully demonstrated sustained delivery of high-quality entangled qubits over 10 miles of real fiber, the roadmap for scaling from two nodes towards a full metropolitan network in cities around the world has become much clearer. As Frank Sinatra sang, “If I can make it there, I'll make it anywhere. It's up to you. New York, New York… ”

Qunnect’s GothamQ testbed serves as a unique real-world laboratory for piloting protocols and use cases with both academic and industry partners. Drop us a line if you’re interested in learning more.