  We present a circuit construction for a new fixed-frequency superconducting
qubit and show how it can be scaled up to a grid with strictly local
interactions. The circuit QED realization we propose implements $\sigma_z$-type
coupling between a superconducting qubit and any number of $LC$ resonators. The
resulting \textit{longitudinal coupling} is inherently different from the usual
$\sigma_x$-type \textit{transverse coupling}, which is the one that has been
most commonly used for superconducting qubits. In a grid of fixed-frequency
qubits and resonators with a particular pattern of always-on interactions,
coupling is strictly confined to nearest and next-nearest neighbor resonators;
there is never any direct qubit-qubit coupling. We note that just four distinct
resonator frequencies, and only a single unique qubit frequency, suffice for
the scalability of this scheme. A controlled phase gate between two neighboring
qubits can be realized with microwave drives on the qubits, without affecting
the other qubits. This fact is a supreme advantage for the scalability of this
scheme.
