Young's interference experiment: Past, present, and future

The celebrated experiment of Thomas Young has had a tremendous historical influence by revealing not only the wave character of light, but also by demonstrating the wave-particle duality that was suggested by de Broglie. In addition, the foundations of coherence theory are based on observable quantities that can be measured in a two-pinhole setup. Remarkably, even after two centuries, the experiment remains strikingly relevant. In recent years it has been used to elucidate the role of surface plasmon polaritons in optical transmission and their influence on spatial coherence. Furthermore, a multipinhole configuration was used to illustrate the connections between various types of field patterns that are the subject of singular optics. Also, the setup continues to provide new insight into the interrelation between entanglement, duality, and nonclassical paths. In this review we discuss the history and the recent applications of Young's experiment and its various incarnations. A closely related form of wavefront division and recombination, namely the Mach–Zehnder interferometer, also figures prominently in our tale.