IBM and Cisco Systems Thursday said they plan to link quantum computers over long distances, with the goal of demonstrating the concept is workable by the end of 2030.

The move could pave the way for a quantum internet, though executives at the two companies cautioned that the networks would require technologies that do not currently exist and will have to be developed with the help of universities and federal laboratories.

Quantum computers hold the promise of solving problems in physics, chemistry and computer security that would take existing computers thousands of years. But they can be error-prone and making a reliable one is a challenge that IBM, Alphabet's Google and others are pursuing. IBM is seeking to have an operational machine by 2029.

Earlier this year, Cisco opened a lab to investigate how to connect quantum machines.

The challenge begins with a problem: Quantum computers like IBM's sit in massive cryogenic tanks that get so cold that atoms barely move. To get information out of them, IBM has to figure out how to transform information in stationary "qubits" — the fundamental unit of information in a quantum computer — into what Jay Gambetta, director of IBM Research and an IBM fellow, told Reuters are "flying" qubits that travel as microwaves.

But those flying microwave qubits will have to be turned into optical signals that can travel between Cisco switches on fiber-optic cables. The technology for that transformation - called a microwave-optical transducer— will have to be developed with the help of groups like the Superconducting Quantum Materials and Systems Center, led by the Fermi National Accelerator Laboratory near Chicago, among others.

Along the way, Cisco and IBM will also publish open-source software to weave all the parts together.

"We are looking at this end-to-end as a system ... rather than two discrete road maps," said Vijoy Pandey, senior vice president of Cisco's Outshift innovation incubator. "We are solving it jointly, which has a much better chance of this thing going in the same direction."