Figure 1
APS/Alan Stonebraker

Figure 1: Three different experiments demonstrate the distribution of entanglement with a nonentangled carrier. The general scheme is to first initiate three photons or three light beams (A,B,C) in separable states. Alice takes A and C and puts them through a kind of interference process, which creates a correlation between them, but not entanglement. The resulting C is then sent to Bob, who combines it with his B. In the final analysis, A and B are entangled, even though the carrier (C) was never entangled with either.