Inside a company selling quantum entanglement

Medhi Namazi wants to sell you quantum entanglement.

He and his colleagues at Qunnect have spent nearly a decade building devices that make sharing quantum entangled particles of light, or photons, practical enough to be used for unhackable communication.

At Qunnect’s headquarters in Brooklyn, New York, large tables are filled with lasers, lenses, special crystals and other tiny components that researchers use to manipulate light. All of them are destined to be neatly packed in light magenta boxes and then shipped off to other creators of the communication technologies of the future.

Against the backdrop of New York’s breathtaking skyline, Namazi opens the box for me, revealing electronics that don’t look particularly remarkable at first glance. But if you stack a few of these boxes together, you get what the company calls a Carina rack—and Carina racks can make remarkable amounts of things happen.

In February, Qunnect’s team used these racks to perform an “entanglement swap” over 17.6 kilometers of fiber optic cables connecting Brooklyn and Manhattan through a commercial data center.

Entanglement swapping is when the property of quantum entanglement is transferred from one pair of photons to another. When photons are entangled, they are extremely sensitive to any attempts to manipulate them, making it nearly impossible to secretly steal the information stored within them. With the exchange, it is then possible to extend this unhackable property to a remote quantum internet.

Qunnect reliably exchanged quantum entanglement between 5,400 pairs of photons every hour as the network ran autonomously for several days. Previous best experiments exchanged entanglements at half or less speed.

Before the Carina stand can perform its tricks, the entangled photons must be created by a separate device. I look at the heart of this “source of entanglement” and see a small glass and metal box filled with a pair of rubidium atoms that must be hit with laser light to produce photon pairs. The smallest details matter here. Namazi tells me how his team was able to increase the number of entangled photons they produced by adjusting the angle at which the laser beams enter the box.

Once the pairs are created, the Carina rack then sends them through a network of fibers throughout New York, to labs at New York University and Columbia University, for example.

Namazi explains how I could set up my own entanglement sharing system if, for example, I wanted to send super secure messages to a friend. “If you have two of them. [Carina] racks, you can have entanglement distribution within hours,” says Namazi.

Qunnect operates one such rack in a commercial data center in Manhattan operated by telecommunications company QTD Systems. When I ask about QTD Peter Feldman on this he matches Namazi’s sentiment. “I don’t need to know anything about quantum physics,” he says. The devices that keep the entangled photons running in the Qunnect network can be controlled remotely, and the process can run autonomously for weeks at a time.

Attempts to build an impenetrable quantum internet are not unique to New York. Several other metropolitan quantum networks exist around the world, including in Hefei, China, and Chicago, Illinois. In any case, there is still work to be done to reach its full potential, including solving the problem that photons are often lost over long distances.

But Namazi says having access to quantum entanglement can already be useful. The entangled photons can be mixed into streams of classical information-carrying light and act as a quantum tripwire of sorts, exposing any nefarious attempts to intercept it.

Another short-term use could be to confirm the identity of a person you’re sharing sensitive information with based on their location, he says Alexander Gaeta at Columbia University, which works with Qunnect. This is again possible due to the quantum nature of entangled photons. In one New York City borough alone, there are dozens of financial institutions that could benefit from such capabilities, he says Javad Shabani at New York University. “Once you have the infrastructure, the end users will come and they’re probably across the street.”

Although the quantum internet is still far from mainstream, driving from Qunnect headquarters to the QTD data center I am struck by how much is already in operation. As I cross one of New York’s bridges, I wonder how many entangled photons have also done the same. Quantum busy New Yorkers with places to be.

topics:

• Internet/
• quantum computing