May 19, 2026

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Quantum computing is reaching its make-or-break moment

Will computers based on quantum physics really change the world?

By Adam Becker edited by Clara Moskowitz

The IBM Quantum System Two, a modular quantum computer, as seen in 2025 at the IBM Thomas J. Watson Research Center in Yorktown Heights, N.Y.

Angela Weiss/AFP/Getty Images

This article is part of a package on the future of quantum computing. Read about the most promising applications of these machines here and see an illustrated field guide to qubits here.

Inside a low-slung building in an office park near the southeastern edge of the San Francisco Bay, a cluster of white tanks sit bathed in blue light. Within these tanks are sets of superconducting circuits etched into chips, all held by golden chandelierlike structures and cooled by liquid helium and liquid nitrogen. The superconducting chips are fabricated in the clean room next door, where white-suited figures work with room-size machinery, fume hoods and acid baths. The facility—the chips, the tanks, the clean room and the enormous reserves of liquid nitrogen behind the building—are all deployed in service of a single dream: quantum computers.

This location is the main fabrication plant for quantum computing company Rigetti Computing in California; each refrigeration tank contains one of Rigetti’s top-of-the-line quantum processing units. One day quantum computers will be able to perform certain kinds of computations orders of magnitude more quickly than the classical computers all around us, experts hope. “We’re talking a million [or a] billion times faster at a very, very small fractional energy consumption,” Rigetti’s CEO, Subodh Kulkarni, tells me. “That’s the beauty of quantum computing. We can potentially solve problems that are unsolvable today.”

Rigetti is just one of dozens of outfits hoping to capitalize on the possibilities. Over the past 20 years start-ups such as Rigetti and giants such as IBM and Google have invested big money in quantum computing—$1.2 billion from venture capitalists in 2023 alone. It’s a major subject of research at universities and government laboratories around the world. All of them are chasing the dream, but the details of that dream depend on whom you ask. Venture capitalists and other purveyors of Silicon Valley hype are promising that quantum computing will supercharge artificial intelligence, or vice versa, but experts are unconvinced of these claims. Kulkarni and others talk about quantum computers revolutionizing drug discovery, weather forecasting and the financial industry. Governments prize their promised abilities to crack heretofore unbreakable codes.

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But none of these predictions are certain. Quantum computing is reaching its make-or-break moment: Scientists hope that in the next few decades they’ll be able to scale up today’s quantum systems to the size needed to make real breakthroughs and finally beat classical machines at useful tasks. If they can do that, quantum computers may change the world in all kinds of ways. But plenty of obstacles stand in the way, and until quantum computers can overcome them, we won’t know what they’re really capable of.

What, exactly, is a quantum computer? It’s tempting to say it’s a computer that runs on the principles of quantum physics. But that isn’t adequate—quantum physics governs the behavior of all matter, so all computers would be quantum computers by this definition. Similarly, it’s not enough to say a quantum computer is a computer that takes advantage of quantum phenomena in its operation. Nearly all computers today run on silicon transistors, the workings of which we can understand only through quantum physics.

To truly answer the question of what makes quantum computers quantum—and why they’re so hard to build—we need to talk about Schrödinger’s cat. In the original thought experiment developed in the 1930s by Erwin Schrödinger, one of the founders of quantum mechanics, the famous feline is sealed in a box with a lump of radioactive metal, a vial of poison, and a contraption that will smash the vial if it detects any radiation from the metal, killing the cat. Quantum physics dictates that if you leave the box sealed for a certain amount of time, there will be a 50–50 chance that the metal lump will have emitted some radioactivity. But, crucially, until someone measures the radiation, the lump is in a superposition: a state in which the radiation has been both emitted and not emitted. And that mea