Feature

Quantum Computing Myths and Reality

Few technologies are surrounded by as much confusion as this one. Here are ten of the most common quantum computing myths, set against what the science and the engineering actually show.

A quantum computer will not replace your laptop. It is a specialised accelerator for a narrow class of problems. For everything you do today, a classical machine is faster and cheaper.

It does not try every answer at once. Superposition is not parallel search. Interference has to cancel the wrong answers, and designing that cancellation is the whole difficulty of a quantum algorithm.

Encryption is not falling this year. The best current estimate for breaking RSA-2048 is under a million noisy qubits, and no machine has more than about twelve hundred. The risk that matters is data stolen today and decrypted later.

More qubits does not mean a better machine. Error rate, connectivity and coherence time decide what a chip can run. A noisy thousand-qubit device can be less useful than a clean fifty-qubit one.

Quantum supremacy was never a claim of usefulness. It means a machine did something a classical computer finds hard, on a task chosen to be hard. None has yet solved a problem anyone needed solved.