  In this paper we derive an effective master equation and quantum trajectory
equation for multiple qubits in a single resonator and in the large resonator
decay limit. We show that homodyne measurement of the resonator transmission is
a weak measurement of the collective qubit inversion. As an example of this
result, we focus on the case of two qubits and show how this measurement can be
used to generate an entangled state from an initially separable state. This is
realized without relying on an entangling Hamiltonian. We show that, for {\em
current} experimental values of both the decoherence and measurement rates,
this approach can be used to generate highly entangled states. This scheme
takes advantage of the fact that one of the Bell states is decoherence-free
under Purcell decay.
