Ramana Kompella, vice president and head of research at Cisco, is a strong evangelist for the nascent quantum internet, which will eventually connect quantum computers nationwide — and even worldwide.
Cisco aims to “build high-fidelity quantum networks to unlock the potential for large-scale quantum data centers,” Kompella told Telecompetitor in an interview. The company is working closely with IBM on the research, with IBM’s role focused primarily on the computing side, while Cisco tackles the networking side.
Quantum computers use concepts of quantum physics. They’re more powerful than traditional non-quantum computers, known in quantum jargon as “classical” computers. But, as of today, there is no way to network quantum computers.
Some developers have established point-to-point connections, but there are no true networks, according to Kompella. That’s where Cisco’s work comes in.
“Where the quantum industry is now is kind of where the classical industry was in 1960,” said Kompella, in a reference to mainframe computers, which were standalone devices.
Ultimately, the industry determined that connecting multiple smaller computers was a better approach than building bigger mainframes. And Kompella sees quantum network development following the same path.
Cisco has also identified use cases for the quantum internet, even when it is used for classical computing. These use cases involve financial trading, secure geographic position verification, time synchronization, and protection against eavesdropping.
Quantum internet challenges
Building a quantum internet won’t be easy, however.
Quantum computers currently operate at sub-Kelvin temperatures, close to absolute zero, and require refrigeration. Clearly, it won’t be practical to refrigerate an entire path between geographically separate data centers.
Cisco has already made progress on that front. Several months ago, the company introduced an entanglement chip that doesn’t require refrigeration.
Entanglement is a critical concept in quantum networking. It involves establishing a connection between pairs of geographically separate sub-atomic particles. That connection is known as entanglement, and once it is established, any changes made at one end of the connection will happen immediately at the other end of the connection as well.
The new Cisco chip is designed to establish these connections over telecom fiber wavelengths at distances as great as 100 kilometers.
Entanglement needs a new protocol stack
If you think about the concept of entanglement, another quantum internet challenge becomes clear: You still need classical networking, which will underpin quantum networks. But you also need something more than a classical network protocol stack.
In classical networks, data is transported from point to point using circuits or packets. Among other things, network protocols define those circuits or packets.
In quantum networking, data isn’t transmitted in the way that we usually think. Instead, computations happen and data appear simultaneously at both ends of the entangled pair. But first, the entanglement must be established, and the new protocols will play a key role in making that happen.
Kompella explained another challenge: Entanglement is fragile.
“You have to build the protocol so that if there are issues, you can recover,” he said.
That fragility also imposes distance limitations on quantum networks. Endpoints can be no more than 100 kilometers apart (a topic Telecompetitor has also discussed with utility and broadband provider EPB, which operates a quantum network testbed in Chattanooga). Longer-distance networks will require quantum repeaters, which have yet to be developed.
Taking all these factors into account, it’s not surprising that Cisco and IBM expect networked distributed quantum computing to be a reality no sooner than the early 2030s.
In the meantime, Kompella seems to be having a great time heading up the team that is working to solve these challenges.
“It’s exciting times for us because it’s almost like you’re reinventing all the things you built for classical computing except with a quantum lens,” he said. “It’s really exciting for Cisco because we’ve done this for the last 40 years.”
