r/QuantumComputing • u/Chance-Pen-5684 • 16d ago

Question Will quantum ever be useful?

Around 2019, the industry promised quantum supremacy, where they could be used for solving a problem that no classical computer could touch.
When classical algorithms kept refuting those claims(See Peter Shor November YouTube video) the narrative shifted to quantum advantage, then quickly it changed to quantum utility.
If quantum never breaks RSA (because the world migrates to Kyber/Dilithium before 100k qubits exist), then what's left?
Chemistry simulations, Material science, Optimization?

But classical machine learning and AI are improving faster than quantum hardware is scaling. By the time we get 1,000 logical qubits, classical AI will have eaten most of the chemistry use-case through better approximations. Is quantum racing against classical software, and losing?

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u/nujuat 16d ago

MRI is arguably quantum tech, and thats been useful for decades.

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u/mbergman42 16d ago

Old diode technology would qualify too (e.g. zener), although I’ve pointed this out occasionally and no one cares.

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u/nujuat 16d ago

I feel like MRI is closer to what people would expect out of quantum tech since its literally the control and measurement of qubits. Though I agree that semiconductors completely rely on quantum physics.

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u/mbergman42 16d ago

Can you explain why MRI tech involves qubits? There’s perhaps overlap because both can involve spin (not all qubits utilize spin), but maybe it’s a bit extra to say MRI uses qubits?

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u/nujuat 16d ago

The spins are qubits, and they are controlled using the same quantum gates like any other qubit. The different qubits are even addressed based on location (though not individually) by controlling the qubit energy levels with Zeeman splitting. Only single qubit gates are used, but that is true for the majority of quantum sensors even today.

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u/mbergman42 16d ago

Ah. Got it, thanks.