Fig. 7: Passing-subroutine for adding new photons to an existing graph, G.
From: Heralded photonic graph states with inefficient quantum emitters
a A graph transformation of passing a new photon (green) from the emitter (red) to an auxiliary spin (black), which is connected to one or more previously added photons (white, denoted with a double edge for the multiplicity). This subroutine consists of two variations: (left) leaving all previously added photons invariant, (right) transplanting those edges to the newly added photon. b An example of how local complementations on a target qubit (magenta circle) can be used to add or remove edges. c A quantum subcircuit which implements the graph transformation. The right variation of the graph transformation above is achieved with the additional two local complementations (blue dashed line, depicting the deviation). Rotations and measurements follow the same notation as in Fig. 6.
