Quantum Non-Demolition Measurements: a New Resource for Making Linear Logic Scalable.

We discuss a novel approach to the problem of creating a photon number resolving detector using the giant Kerr nonlinearities available in electromagnetically induced transparency. Our scheme can implement a photon number quantum non-demolition measurement with high efficiency (>99%) which can distinguish 0, 1 and 2 photons. We then show how it is possible to construct a near deterministic CNOT using several single photons sources, linear optics, photon number resolving quantum non-demolition detectors and feed-forward. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]