Resonant Two-Qubit Gates and Mesoscopic Shelving Qubit Readout in Circuit QED*

We consider the implementation of universal sets of resonant one-qubit and two-qubit gates for superconducting qubits inside microwave resonators in Circuit QED, aiming at the speed-up of gate operations [1]. We study also the implementation of mesoscopic shelving readout of a superconducting qubit inside a microwave resonator, where a high-fidelity measurement may be achieved [2]. In both proposals we borrow from inspiring quantum-optical tools and concepts, exploiting the advantages of three-level physics and adapting electron-shelving readout in a novel manner in the context of multi-cavity physics [3], and in particular two-cavity Circuit QED [4]. \\[4pt] REFERENCES: \\[0pt] [1] G. Haack, F. Helmer, M. Mariantoni, J. von Delft, F. Marquardt, and E. Solano, ``Resonant toolbox of universal quantum gates in Circuit QED'', in preparation. \\[0pt] [2] B. Englert, G. Mangano, M. Mariantoni, R. Gross, J. Siewert, and E. Solano, ``Mesoscopic Shelving Qubit Readout in Circuit QED'', in preparation. \\[0pt] [3] F. Helmer, M. Mariantoni, A. G. Fowler, J. von Delft, E. Solano, and F. Marquardt, ``Two-dimensional cavity grid for scalable quantum computation with superconducting circuits'', arXiv:0706.3625. \\[0pt] [4] M. Mariantoni, F. Deppe, A. Marx, R. Gross, F. K. Wilhelm, and E. Solano, ``Two-resonator circuit quantum electrodynamics: A superconducting quantum switch'', Phys. Rev. B 78, 104508 (2008).