The Hanbury Brown and Twiss (HBT) effect refers to a quantum phenomenon that is observed in the measurement of intensity correlations of light waves, particularly in the context of photon statistics. This effect was first studied by physicists Robert Hanbury Brown and Richard Q. Twiss in the 1950s when they were investigating the characteristics of light from stars and other sources.
Articles by others on the same topic
Robert Hanbury Brown and Richard Q. Twiss sought angular sizes through correlations of detected light intensities. Their method multiplies detector outputs after detection, whereas a Michelson interferometer combines fields before detection.[ref]
Correlation between Photons in two Coherent Beams of Light by Robert Hanbury Brown and Richard Quentin Twiss. 1956, Nature 177, pp. 27–29, accessible opening paragraphs
A monochromatic discharge source illuminated a half-silvered beam splitter and two photodetectors. The averaged current product showed an excess near coincidence. Moving one detector introduced a delay that removed it, supplying a control. Slow response weakened the peak. This photon bunching is compatible with fluctuating classical light intensity.[ref]
One Hundred Years of Light Quanta by Roy Jay Glauber. 2005 individual Nobel lecture, pp. 86–88, figures 3–4