  We introduce a scheme to perform quantum-information processing that is based
on a hybrid spin-photon qubit encoding. The proposed qubits consist of
spin-ensembles coherently coupled to microwave photons in coplanar waveguide
resonators. The quantum gates are performed solely by shifting the resonance
frequencies of the resonators on a ns timescale. An additional cavity
containing a Cooper-pair box is exploited as an auxiliary degree of freedom to
implement two-qubit gates. The generality of the scheme allows its potential
implementation with a wide class of spin systems.
