Entanglement concentration of weighted graph states

The creation of graph states is highly demanding because of the experimental error in the required gates. An experimentally relevant scenario is a coherent two-qubit error, which results in a gate with reduced entangling power. This in turn leads to weighted graphs, which contain less entanglement than regular graph states. We propose an entanglement concentration protocol that is capable of generating perfect GHZ states with a few local measurements on weighted graph states. We analyze how our protocol efficiently generates GHZ states and how robust these states are in the presence of noise.