1. A method of forming a quantum error-correcting code for a quantum information processing system, comprising: selecting quantum basis operators operable to act upon quantum states in a specified space and to represent an arbitrary operator which is applicable to said specified space; determining error syndromes indicative of errors caused by operations and perturbations on any of said quantum states in said specified space, wherein said operation and perturbations can be represented by combinations of said basis operators; forming a plurality of stabilizer operators for a coding subspace of said specified space according to said error syndromes in such a way that said stabilizer operators are operable to detect and correct said errors, wherein said stabilizer operators commute with one another and an eigen value of a square of each of said stabilizer operators in said specified space is +1; and constructing code words in said coding subspace by using said stabilizer operators to operate on a plurality of selected states.