Quantum optics with superconducting qubits in the dispersive limit

Andreas J. Wallraff, David Schuster, Alexandre Blais +10 more

In this paper, the coherent interaction of individual microwave photons with superconducting qubits is presented both for quantum information processing and for novel quantum optics experiments in the circuit quantum electrodynamics (QED) architecture. In the resonant regime we observe the vacuum Rabi mode splitting. In the non-resonant regime we use the dispersive coupling between the qubit and the cavity field to perform high visibility quantum non-demolition (QND) measurements of the qubit state. In the strong dispersive limit we also perform measurements of the cavity state from which the photon number statistics of the field can be extracted. Generally, the circuit QED architecture is attractive for quantum information processing and as an interface in hybrid quantum systems.

Andrew L. DiRienzo, Daniel N. Rogovin, Marlan O. Scully +3 more

Maxwell D. Urmey, Robert D. Delaney, Sarang Mittal +9 more

We perform dispersive readout of a superconducting qubit using optical heterodyne detection via a mechanical electro-optic transducer, without causing significant backaction on the qubit. This is a key milestone in linking remote superconducting quantum processors.

Robert H. Hadfield, Göran Johansson

Simon E. Nigg, S. M. Girvin

We present a general protocol for stabilizer measurements and pumping in a system of N superconducting qubits. We assume always-on, equal dispersive couplings to a single mode of a high-Q microwave resonator in the ultra-strong dispersive limit where the dispersive shifts largely exceed the spectral linewidth. In this limit, we show how to map the two eigenvalues of an arbitrary weight M < N Pauli operator, onto two quasi-orthogonal coherent states of the cavity. Together with a fast cavity readout, this enables the efficient measurement of stabilizer operators.