Stevens Switches On the Nation’s First Campus Hybrid Quantum-Communications Network
A Stevens physics team deploys and verifies a pathbreaking three-node quantum communications network, paving the way for super-secure communications.
Late at night, a driver veers off a highway to avoid a collision — safely, but just barely. That same instant, the driver’s twin sibling, thousands of miles away, wakes in a cold sweat with a terrible premonition about a car accident and rushes to call the driver.
That’s more or less how the spooky, yet all-too-real, world of quantum communication works.
Stevens’ Center for Quantum Science and Engineering (CQSE), led by physics professor Yuping Huang and a graduate student team, has built one of the first demonstrations of the ways the quantum concept might help us address grand societal challenges such as cybersecurity.
First the CQSE team completed a line-of-sight quantum link across a campus street to the high-tech Hanlon 2 financial lab in the university’s Babbio Center. Then, in 2018, a third node was completed, tested and verified: a quantum link, via underground fiber-optic cables, to a kiosk on the first floor of the S.C. Williams Library.
Now the Stevens team plans to make the system smaller — so that it could one day fit in a phone or a laptop — yet more powerful.
“The physics have long been known, and the concept has been proven in experiments, including using a satellite,” notes Huang. “But the engineering of this, in a cost-effective manner that could scale widely, has proven to take more time.”
The system works like this: a laser in the Burchard Building creates twin photons in a lithium niobate waveguide. Photons produced are routed simultaneously both to Babbio and to the library via different pathways. Detectors at each of the three locations flag individual photons and create private keys for data encryption, which can then be used to encrypt data, communications or physical devices.
It all works because of entanglement: the idea that, whenever any manipulation is made to one photon, its sibling also responds and changes as a result.
“In plain terms, if you create a pair of twin photons, and then measure what happens at the library, you don’t even have to go over to Babbio to find out what measurement outcome the photon in Babbio would have, because it will be predictable,” says Stevens postdoctoral researcher Yong Meng Sua. “It’s remarkable.”
Potential applications of quantum communications, if the technology can be harvested and scaled up, include ultra-secure financial transactions as well as defense, medical and other sensitive data storage and computation.