Hanbury Brown and Twiss experiment

The Hanbury Brown and Twiss experiment, conducted in 1956, demonstrated a unique property of light, showing that photons (light particles) could exhibit "bunching" behavior. When two beams of light from the same source were sent through a beamsplitter and measured, they found that photons were more likely to arrive in pairs rather than randomly. This result challenged the conventional understanding of light as consistent and independent, suggesting that photons could have a degree of correlation. The experiment laid the groundwork for advancements in quantum optics, enhancing our understanding of light and its fundamental properties.