  We discuss the prospect of using quantum properties of large scale Josephson
junction arrays for quantum manipulation and simulation. We study the
collective vibrational quantum modes of a Josephson junction array and show
that they provide a natural and practical method for realizing a high quality
cavity for superconducting qubit based QED. We further demonstrate that by
using Josephson junction arrays we can simulate a family of problems concerning
spinless electron-phonon and electron-electron interactions. These protocols
require no or few controls over the Josephson junction array and are thus
relatively easy to realize given currently available technology.
