#logical-qubits

The big-picture architecture: noisy physical qubits, error-corrected logical qubits, fault-tolerant machines, and how industry roadmaps map onto all three.

How many imperfect physical qubits become one reliable logical qubit: the surface code, code distance, the threshold, decoding, and why raw qubit counts mislead.

Noise, decoherence, gate errors, measurement errors, crosstalk and environmental interference explained, plus how quantum error correction makes qubits reliable.