At the end of last year, the tech giant IBM announced what might sound like a milestone in quantum computing: the first-ever chip, called the Condor, with more than 1,000 quantum bits, or qubits. Given that this was barely two years after the company unveiled the Eagle, the first chip with more than 100 qubits, it looked as though the field was racing forward. Making quantum computers that can solve useful problems beyond the scope of even the mightiest of today’s classical supercomputers demands scaling them up even more — to perhaps many tens or hundreds of thousands of qubits. But that’s surely just a matter of engineering, right?

Not necessarily. The challenges of scaling up are so great that some researchers think it will require totally different hardware from the microelectronics used by the likes of IBM and Google. The qubits in the Condor and in Google’s Sycamore chip are made from loops of superconducting material. These superconducting qubits have so far been the hare in the race to full-scale quantum computing. But now there’s a tortoise coming from behind: qubits made from individual atoms.

Recent advances have transformed these “neutral-atom qubits” from outsiders to leading contenders.

“The last two or three years have seen more rapid advances than any previous such period,” said the physicist Mark Saffman of the University of Wisconsin, Madison, who counted at least five companies racing to commercialize neutral-atom quantum computing.

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