Stony Brook, BNL unveil new tech to enhance power of quantum computing

They’re not your grandfathers’ lighthouses.

Researchers at Stony Brook University and Brookhaven National Laboratory on Friday demonstrated the transmission of light particles containing quantum information in what they called a first-of-its-kind step in "extending the nation’s longest quantum network."

The ability to link infinitely more complex quantum computers via specially designed quantum "lighthouses" such as those at Stony Brook and Brookhaven lab is crucial to aggregating their combined power, researchers said.

The plan is ultimately to allow the computers to work together across the country to "tackle some of the nation’s most pressing scientific challenges," BNL said. The next stop involves linking a similar quantum lighthouse across Long Island Sound at Yale University.

"The future of quantum information science will depend not only on what individual quantum computers and devices can do, but on our ability to connect them," Department of Energy Under Secretary for Science Darío Gil said at the demonstration at BNL Friday, calling it a "remarkable first" for the county. 

"This achievement opens a vital new pathway for connecting quantum systems across distances in ways that fiber can't achieve," he said, adding that the work will eventually pave the way for advanced quantum satellite connections. "Quantum capabilities become more useful when we can connect them," he said. 

To accomplish their work, researchers at BNL and Stony Brook powered up a laser to "generate quantum states of light," each with a few individual photons, the lab said. One of the researchers, Justine Haupt, described the elation she felt when the first photon signals crossed the 13-mile gap in darkness early Wednesday morning. 

Stony Brook sent the signals from its "Quantum Watchtower," located on the roof of the university’s Health Science Center. The photons left that device via an optical fiber thinner than a human hair and traveled via a line-of-sight beam to a tiny receiving camera atop Brookhaven’s Quantum Lighthouse on the BNL campus.

SBU President Andrea Goldsmith, in an interview, said that while it will be a "few more years" before the breakthrough results in widespread commercial use of the technology, the work portends a coming revolution in quantum computing. 

Quantum computers, she noted, "allow you to do computations that would take you a lifetime to do" using conventional computers. Goldsmith pointed to implications in drug discovery, development of new materials, stock market predictions — "things it would take a classical computer years or decades to do you can do in minutes" with quantum computers, which leverage the laws of physics. 

Linking quantum computers by the new networks "supercharges quantum computing," she added, and does it in a secure way that cannot be hacked. 

Even as they announced the milestone, BNL said the researchers have already progressed to the "next phase of experimentation," using what they called "entangled photons," or pairs of light particles that are "intrinsically linked by the laws of quantum mechanics."

Researchers have already sent entangled photons from the Stony Brook physics laboratory to the Quantum Watchtower during nighttime tests, they said, distributing them across the new "free-space optical link."

"This is a key advance toward achieving sustained ‘wireless’ exchange of quantum information between the two institutions — and eventually beyond," BNL said.

"The future of quantum science won’t be defined by individual systems alone," BNL Director John Hill said at the event. "It will be defined by how we connect quantum devices together to form distributed systems. The quantum future is a networked future. Today, we’re taking a major step forward toward achieving that vision."

In the new quantum wireless links, researchers are "exploring the use of infrared wavelengths that are native to quantum processors and related technologies," said Eden Figueroa, director of Stony Brook’s Quantum Institute, in a statement. "This will provide a direct route to create entangled atomic systems across long distances."