The invention of the two-photon Clauser interferometer opened a completely new domain of photon spectroscopy. It allowed direct experimental demonstration for the first time of non-local nonrealist phenomena in physics. We will describe this interferometer and analyse its application to the detection of bi-photons, and discuss other phenomena at the interface between classical and quantum physics. One of the consequences is that relaxation is not always what we were taught. Recent experiments on photons  and atoms  demonstrate the difference between local, singleparticle dynamics and non-local dynamics of entangled quantum systems coupled to independent environments. Even when local environment-induced decay of a system is smoothly asymptotic, quantum entanglement may suddenly disappear. This “sudden death” constitutes yet another distinct and counterintuitive trait of entanglement, confirming earlier predictions [3,4].
© 2007 Optical Society of AmericaPDF Article