Brief Communication Arising

Nature 445, E4-E5 (11 January 2007) | doi:10.1038/nature05546; Published online 10 January 2007

Quantum Information: Source of triggered entangled photon pairs?

Alexei Gilchrist1, Kevin J. Resch1,2 & Andrew G. White1

Arising from: R. M. Stevenson et al. Nature 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.1 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.1.

  1. Department of Physics and Centre for Quantum Computer Technology, University of Queensland, Brisbane, Queensland 4072, Australia
  2. Present address: Department of Physics and Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada

Correspondence to: Andrew G. White1 Email:


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