Quantum measurement pulls one classical answer out of a quantum state, and the Born rule of 1926 gives each outcome a probability equal to the squared magnitude of its amplitude. Readout fidelities are quoted above ninety-nine percent, and readout speed sets how fast an error-correction cycle can turn, so hardware teams spend more effort on it than on the qubits.
Quantum Measurement, How Reading a Qubit Works
Quantum measurement pulls one classical answer out of a quantum state, and the Born rule of 1926 gives each outcome a probability equal to the squared magnitude of its amplitude. Readout fidelities are quoted above ninety-nine percent, and readout speed sets how fast an error-correction cycle can turn, so hardware teams spend more effort on it than on the qubits.