Patrick Rall

A quantum computer is like an orchestra: each musician plays their part, but the slightest false note ruins the symphony. The physical qubits it is built from are noisy and error-prone. To protect computations, they are combined into logical qubits using quantum error correction.

A washing machine sometimes tears clothes. To get a whole shirt, you wash several and then piece one together from the survivors. A quantum computer treats 'magic states'—special ingredients without which complex computations are impossible — in much the same way. These states are extremely fragile. The slightest noise, and the magic evaporates.