2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/217147In many physically realistic models of quantum computation, Pauli exchange interactions cause a subset of two-qubit errors to occur as a first order effect of couplings within the computer, even in the absence of interactions with the computer's environment. We give an explicit 9-qubit code that corrects both Pauli exchange errors and all one-qubit errors.Final version accepted for publication in Phys. Rev. LettQuantum PhysicsMathematical Physicstext