Fig. 4
Prototypical extraction of a GHZ4 state. In order to distill a GHZ4 state between the nodes 1, 2, 4 and 5 of a 12 qubit cluster state (a), we Z-measure three nodes (b) and X-measure the four remaining intermediate nodes, thus isolating a repeater line (c) in accordance with Proposition 3. We then perform consecutive local complementations on nodes 2 (d), 3 (e), and 4 (f). Node 3 is finally Z-measured (g) to establish the desired GHZ4 state
