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Illustration Credit: Carl Burton

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Such a device could help address climate change and food scarcity, or break the Internet. Will the U.S. or China get there first?

A quantum computer hovers mysteriously in a cloudy sky flashing on and off like a spaceship.
The potential impact has been called “more profound than any technology to date.”

On the outskirts of Santa Barbara, California, between the orchards and the ocean, sits an inconspicuous warehouse, its windows tinted brown and its exterior painted a dull gray. The facility has almost no signage, and its name doesn’t appear on Google Maps. A small label on the door reads “Google AI Quantum.” Inside, the computer is being reinvented from scratch.

In September, Hartmut Neven, the founder of the lab, gave me a tour. Neven, originally from Germany, is a bald fifty-seven-year-old who belongs to the modern cast of hybridized executive-mystics. He talked of our quantum future with a blend of scientific precision and psychedelic glee. He wore a leather jacket, a loose-fitting linen shirt festooned with buttons, a pair of jeans with zippered pockets on the legs, and Velcro sneakers that looked like moon boots. “As my team knows, I never miss a single Burning Man,” he told me.

In the middle of the warehouse floor, an apparatus the size and shape of a ballroom chandelier dangled from metal scaffolding. Bundles of cable snaked down from the top through a series of gold-plated disks to a processor below. The processor, named Sycamore, is a small, rectangular tile, studded with several dozen ports. Sycamore harnesses some of the weirdest properties of physics in order to perform mathematical operations that contravene all human intuition. Once it is connected, the entire unit is placed inside a cylindrical freezer and cooled for more than a day. The processor relies on superconductivity, meaning that, at ultracold temperatures, its resistance to electricity all but disappears. When the temperature surrounding the processor is colder than the deepest void of outer space, the computations can begin.

Classical computers speak in the language of bits, which take values of zero and one. Quantum computers, like the ones Google is building, use qubits, which can take a value of zero or one, and also a complex combination of zero and one at the same time. Qubits are thus exponentially more powerful than bits, able to perform calculations that normal bits can’t. But, because of this elemental change, everything must be redeveloped: the hardware, the software, the programming languages, and even programmers’ approach to problems.

On the day I visited, a technician—whom Google calls a “quantum mechanic”—was working on the computer with an array of small machine tools. Each qubit is controlled by a dedicated wire, which the technician, seated on a stool, attached by hand.

The quantum computer before us was the culmination of years of research and hundreds of millions of dollars in investment. It also barely functioned. Today’s quantum computers are “noisy,” meaning that they fail at almost everything they attempt. Nevertheless, the race to build them has attracted as dense a concentration of genius as any scientific problem on the planet. Intel, I.B.M., Microsoft, and Amazon are also building quantum computers. So is the Chinese government. The winner of the race will produce the successor to the silicon microchip, the device that enabled the information revolution.

A full-scale quantum computer could crack our current encryption protocols, essentially breaking the Internet. Most online communications, including financial transactions and popular text-messaging platforms, are protected by cryptographic keys that would take a conventional computer millions of years to decipher. A working quantum computer could presumably crack one in less than a day. That is only the beginning. A quantum computer could open new frontiers in mathematics, revolutionizing our idea of what it means to “compute.” Its processing power could spur the development of new industrial chemicals, addressing the problems of climate change and food scarcity. And it could reconcile the elegant theories of Albert Einstein with the unruly microverse of particle physics, enabling discoveries about space and time. “The impact of quantum computing is going to be more profound than any technology to date,” Jeremy O’Brien, the C.E.O. of the startup PsiQuantum, said recently. First, though, the engineers have to get it to work.

Imagine two pebbles thrown into a placid lake. As the stones hit the surface, they create concentric ripples, which collide to produce complicated patterns of interference. In the early twentieth century, physicists studying the behavior of electrons found similar patterns of wavelike interference in the subatomic world. This discovery led to a moment of crisis, since, under other conditions, those same electrons behaved more like individual points in space, called particles. Soon, in what many consider the most bizarre scientific result of all time, the physicists realized that whether an electron behaved more like a particle or more like a wave depended on whether or not someone was observing it. The field of quantum mechanics was born.

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