1. A quantum computing method, comprising: (A) constructing a dressing transformation V between a physical Hamiltonian H and an ideal Hamiltonian H ID, wherein said physical Hamiltonian H describes a physical quantum computer that comprises a plurality of qubits, including interactions between said plurality of qubits and an error source, said ideal Hamiltonian H ID describes a universal quantum computer that corresponds to said physical quantum computer, and, for a dressed state &verbar;&psgr; of said physical quantum computer, said dressing transformation V has the property that &verbar;&psgr; &equals; V † &verbar;&psgr; ID where &verbar;&psgr; ID is an undressed state in the universal quantum computer that corresponds to the given dressed state &verbar;&psgr; of said physical quantum computer, and V † is the Hermitian conjugate of said dressing transformation V; (B) initializing each qubit in said plurality of qubits to a known state; (C) performing a quantum calculation using said plurality of qubits; and (D) measuring said plurality of qubits.