IBM builds 50-qubit quantum computer
IBM has said it has developed a quantum computer capable of handling 50 quantum bits, or qubits, and is making a 20-qubit system available via the cloud. The breakthrough was announced at the recent Institute of Electrical and Electronics Engineers Industry Summit on the Future of Computing in Washington. Dario Gil, director of artificial intelligence and quantum computing at IBM, said the 50-qubit machine was a "big frickin' deal". However, other researchers counselled caution, and said details of the device had not been published or peer-reviewed.

The announcement does not mean quantum computing is ready for common use. The system IBM has developed is still extremely finicky and challenging to use, as are those being built by others. In both the 50- and the 20-qubit systems, the quantum state is preserved for 90 microseconds—a record for the industry, but still an extremely short period of time.

Nonetheless, 50 qubits is a significant landmark in progress toward practical quantum computers. Other systems built so far have had limited capabilities and could perform only calculations that could also be done on a conventional supercomputer. A 50-qubit machine can do things that are extremely difficult to simulate without quantum technology.

Whereas normal computers store information as either a 1 or a 0, quantum computers exploit two phenomena—entanglement and superposition—to process information differently.

“We are really proud of this; it’s a big frickin’ deal,” Dario Gil, who directs AI and quantum computing at IBM, told MIT Technology Review. Gil made the announcement at the IEEE Industry Summit on the Future of Computing in Washington, D.C., on Friday morning.

IBM has a storied history in quantum computing. The company’s researchers helped create the field of quantum information processing, and it has pursued fundamental research in the area for decades.

It has also been making significant progress toward useful quantum systems, first by making quantum computers accessible through the cloud and developing relevant software tools, and second by showing how even a simple machine can do useful work in fields like chemistry (see “IBM Has Used Its Quantum Computer to Simulate a Molecule—Here’s Why That’s Big News”).

IBM is also announcing an upgrade to its quantum cloud software system today. “We’re at world record pace. But we’ve got to make sure non-physicists can use this,” Gil says.

The announcement should perhaps be treated cautiously, though. Andrew Childs, a professor at the University of Maryland, points out that IBM has not published details of its system in a peer-reviewed journal. “IBM’s team is fantastic and it’s clear they’re serious about this, but without looking at the details it’s hard to comment,” he says.