Young's Double-Slit Interference Demonstration with Single Photons

The interference of single photons going through a double slit is acompelling demonstration of the wave and particle nature of light in the sameexperiment. Single photons produced by spontaneous parametric down-conversioncan be used for this purpose. However, it is particularly challenging toimplement due to coherency and resolution challenges. In this article, wepresent a tabletop laboratory arrangement suitable for the undergraduateinstruction laboratory that overcomes these challenges. The apparatus scans asingle detector to produce a plot showing the interference patterns of singlephotons. We include experimental data obtained using this setup demonstratingdouble-slit and single-slit interference as well as quantum erasing through theuse of sheet polarizers.