Advanced information on the Nobel Prize in Physics 2005

Quantum-mechanical theory of optical coherence Laser-based precision spectroscopy and optical frequency comb techniques General introduction Light provides the most pertinent example of the dual nature of quantum objects; its oscillatory properties served to verify the electromagnetic theory of Maxwell, and its lumpiness, the photons, signalled the dawn of modern quantum theory. The electromagnetic phenomena form an integral part of modern technology. They are at work in all electrical motors, and our communication devices utilize their oscillatory behaviour in essential ways. Our radio receivers and mobile phones are all based on the ability of the radiation to sustain well-defined frequency and phase properties. On the other hand, each device detecting the radiation must be based on the absorption of radiation energy into the material medium. This energy is known to occur in packets, which are now called photons. Absorption of a photon will cause the creation of an excitation which may be amplified and detected. Since the work of Einstein in 1905, w