  We describe an assembly of N Cooper-pair boxes (CPB) contained in a single
mode cavity. In the dispersive regime, the correlation between the cavity field
and each Cooper-pair box results in an effective interaction between CPBs that
can be used to dynamically generate maximally entangled states. With only
collective manipulations, we show how to create maximally entangled quantum
states and how to use these states to reach the Heisenberg limit in the
determination of a spectroscopy frequency. This scheme can be applied to other
types of superconducting qubits.
