Abstract
Triggered single-photon sources produce the vacuum state with nonzero probability, but produce a much smaller multiphoton component. It is therefore reasonable to approximate the output of these photon sources as a mixture of the vacuum and single-photon states with probabilities and , respectively. Here we are concerned with increasing the efficiency by directing multiple copies of the single-photon-vacuum mixture into a linear optical device and applying photodetection on some outputs. We prove that it is impossible, under certain conditions, to increase via linear optics and conditional preparation based on photodetection. We also establish a class of photodetection events for which can be improved, although with an added multiphoton component. In addition we prove that it is not possible to obtain perfect single-photon states via this method from imperfect inputs.
- Received 23 September 2003
DOI:https://doi.org/10.1103/PhysRevA.69.031806
©2004 American Physical Society