Abstract
Probabilistic quantum nondemolition (QND) measurements can be performed using linear optics and postselection. Here we show how QND devices of this kind can be used in a straightforward way to implement a quantum relay, which is capable of extending the range of a quantum cryptography system by suppressing the effects of detector noise. Unlike a quantum repeater, a quantum relay system does not require entanglement purification or the ability to store photons.
- Received 3 May 2002
DOI:https://doi.org/10.1103/PhysRevA.66.052307
©2002 American Physical Society