Northwestern University physicists have introduced a new approach to stabilize quantum networks by rebuilding disappearing connections. Their research, published in the journal Physical Review Letters, explores how adding an optimal number of connections can maintain network functionality without overwhelming resources.
"Many researchers are putting significant efforts into building larger and better quantum communication networks around the globe," said István Kovács, the study's senior author and assistant professor at Northwestern's Weinberg College of Arts and Sciences. He explained that quantum networks often collapse as soon as they are used because links disappear after each communication event. The team developed a model where additional links were added between disconnected nodes to sustain connectivity.
Quantum entanglement is central to these networks, allowing particles to remain linked regardless of distance. Xiangi Meng, one of the study's first authors and now an assistant professor at Rensselaer Polytechnic Institute, described it as "the spooky, space-time-defying correlation between quantum particles."
The research aimed to determine the exact number of links needed after each communication event to prevent network fragmentation. Surprisingly, they found this critical number is just the square root of the number of users in the network. For example, if there are 1 million users, 1,000 links must be re-added for every qubit sent.
Kovács believes this finding could guide others in designing robust quantum networks capable of withstanding failures by automatically adding new links when others vanish.
"The classical internet was not built to be fully robust," Kovács noted. "But now we can do better with the quantum internet."
The study was supported by the National Science Foundation under grant number PHY-2310706.