The problem with photon detectors is that they can be noisy or have a limited ability to detect single photons. Some cannot identify the number of photons; they can only detect their presence. Given the influence of these factors, improving the fidelity of single-photon generation is very challenging. But it is also crucial for their subsequent use in quantum information protocols, including quantum communication and computing.
Single photons are typically generated using two laser beams that are correlated at the quantum level. This means that the detection of a single photon in the first beam heralds the generation of a single photon in the second one.
The authors first reviewed how to describe a detector from a mathematical point of view. They then simulated which photons would be obtained from different initial sources. This led the team to outline the conditions under which the heralding detector can deliver good resolution of the number of photons, as a means of improving the reliability in obtaining single photons. They corroborated their findings using two experimental detectors.
V. D'Auria, O. Morin, C. Fabre, J. Laurat are the authors of the paper, titled "Effect of the heralding detector properties on the conditional generation of single-photon states" which appears in theEuropean Physical Journal D, DOI 10.1140/epjd/e2012-30351-6.