Photons

Polarized light is often used in QIS and QC applications. The quantum nature of light manifests itself in the empirical observation that light is made up of small, discrete bundles of energy. Those bundles are called photons. The discovery of the photon nature of light was one of the most fundamental and important experiments leading to the development of quantum mechanics early in the 20th century. Ordinary light beams transmit billions and billions of photons per second, so in most everyday situations, we don’t notice the individual photons.