Quantum Information: Source of triggered entangled photon pairs?

Arising from: R. M. Stevenson et al. 439, 179-182 (2006); Stevenson et al. reply. The realization of an entangled photon source will be of great importance in quantum information - for example, for quantum key distribution and quantum computation - and Stevenson et al. have described such a source. However, we show here that first, their source is not entangled; second, they use inappropriate entanglement indicators that rely on assumptions invalidated by their data; and third, their source has insignificant entanglement even after simulating subtraction of the significant quantity of background noise. We therefore find that the standard of proof required for a semiconductor source of triggered entangled photon pairs has not been met by Stevenson et al..