Colloquium on December 18th, 2006

Han Woerdman
Huygens Laboratory, Leiden University

Entangled photons

The most prominent feature of two entangled particles is that the show quantum nonlocality. On the one hand, this made Einstein doubt whether quantum mechanics is complete; on the other hand this feature is effectively exploited in quantum information science. Photons are particularly suitable for experimental tests of entanglement in view of the advanced state of the art of quantum-optics technology. Possible applications of photonic entanglement are in quantum communication, e.g. in quantum cryptography (already commercially available) or in connecting two quantum computers (in the future).

After introducing these issues we will focus on some examples taken from our own work. We explore the properties of entangled photons in a wide range of condensed-matter light scattering systems. These include dispersed media, surface plasmons and optical vortices. The common aspect of these examples is the key role played by the spacial degrees of freedom of the entangled photons.