2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/90992The main ideas of quantum error correction are introduced. These are encoding, extraction of syndromes, error operators, and code construction. It is shown that general noise and relaxation of a set of 2-state quantum systems can always be understood as a combination of Pauli operators acting on the system. Each quantum error correcting code allows a subset of these errors to be corrected. In many situations the noise is such that the remaining uncorrectable errors are unlikely to arise, and hence quantum error correction has a high probability of success. In order to achieve the best noise tolerance in the presence of noise and imprecision throughout the computer, a hierarchical construction of a quantum computer is proposed.12 pages, a very simple tutorial introduction to error correction, with emphasis on avoiding misconceptions regarding the treatment of noiseQuantum Physicstext