In the '90 researchers in quantum information have developed a theory of quantum error correction and fault-tolerance. This theory shows that quantum mechanics can describe the dynamics of macroscopic objects,
consisting of many elementary degrees of freedom, given a sufficient amount of physical control and a means for entropy removal. We discuss the ideas behind fault-tolerance and challenges towards realizing it, using
illustrations of superconducting transmon qubit experiments. We discuss the alternative idea of encoding qubits into oscillators. We present some of our recent work which formulates a scalable circuit-QED architecture based on such encoding.
