Correlated errors in quantum-error corrections - art. no. 022303

We show that errors are not generated correlatedly provided that quantum bi ts do not directly interact with (or couple to) each other. Generally, this no-qubit-interaction condition is assumed except for the case where two-qu bit gate operation is being performed. In particular, the no-qubit-interact ion condition is satisfied in the collective decoherence models. Thus, erro rs are not correlated in the collective decoherence. Consequently, we can s ay that current quantum error correcting codes that correct single-qubit er rors will work in most cases including the collective decoherence.