  Quantifying experimentally created entanglement could in principle be
accomplished by measuring the entire density matrix and calculating an
entanglement measure of choice thereafter. Due to the tensor-structure of the
Hilbert space, this approach becomes infeasible even for medium-size systems.
In this letter we present methods to quantify the entanglement of arbitrarily
large two-colorable graph states from simple measurements. The measurement data
considered here is merely given by stabilizer measurements, thus leading to an
exponential reduction in the number of measurements required. We provide
analytical results for the robustness of entanglement and the relative entropy
of entanglement.
