  We study a linear array of coupled cavities interacting with two level
systems and show how to construct individually addressable qubits in this
system from the long-lived atom-photon excitations (polaritons) at each site.
We derive the system dynamics and show that is described by an XY Hamiltonian.
We proceed by showing how to implement non-local quantum gates and show that
combined with the inherent ability for individual addressing, universal quantum
computation is possible in this system. We finally discuss the prospects for
experimental implementation using various technologies involving dopants as
atoms, quantum dots or Cooper pair boxes.
