Measuring the entanglement of coupled spins by multiphoton interference

We propose an experimental method to measure the entanglement of coupled spins, each in a separate quantum dot, by means of multiphoton interference patterns generated through the scattering of two laser beams off the quantum dots. We calculate the N-photon quantum correlations measured by N detectors on an image plane. Using two perpendicular laser beams, either many correlation measurements on a time ensemble or a single correlation measurement on a spatial ensemble of the many-qubit state is sufficient to retrieve all the possible amplitudes of a many-qubit state.