October 5, 2005, Stockholm, Sweden--This year the Nobel Prize in Physics was awarded to three scientists in the field of optics: Roy Glauber (Harvard University; Cambridge, MA); John Hall (JILA, University of Colorado and National Institute of Standards and Technology; Boulder, CO); and Theodor Hansch (Max-Planck-Institut für Quantenoptik, Garching and Ludwig-Maximilians-Universitat; Munich, Germany).
Glauber, was recognized for showing how quantum theory must be formulated to describe the detection of electromagnetic radiation. This also served to bring out the distinction between the behaviour of thermal light sources and presently common coherent sources such as lasers and quantum amplifiers, according to the Royal Swedish Academy statement. Glauber's theoretical formulation uses the formalism of quantum electrodynamics to describe the absorption of a photon in a detector. By correlating several such detectors, one may obtain higher order correlations, which can display clearly the characteristic features of quantum radiation."
Hall and Hansch were jointly recognized for contributions to the development of laser-based precision spectroscopy, including the so-called optical frequency comb technique. In addition to having important practical applications, these methods make it possible to determine the quantum structure of matter with ever-increasing accuracy and to test fundamental theories, according to the Royal Swedish Academy statement. Also in precision measurements, quantum effects, manifested as quantum noise, set an absolute limit on system performance.