ABSTRACT
One of the key advantages of the quantum-dot single-photon guns is that we can manufacture them cheaply and in mass quantities – they fit onto a compact circuit board. The quantum dot is grown into a multilayer structure of semiconducting material. Then most of the material is etched away leaving a single micropillar containing the quantum dot between the two mirrors. For applications such as quantum cryptography, for 30 years we have used attenuated laser pulses instead of true single-photon sources. What on earth is an attenuated laser pulse? Recall the requirement of photons guns. They must produce one and only one photon per shot and never fire blanks. To make a pseudo-single-photon gun, one must attenuate the laser, pass it through an absorbing filter, so that the output contains, on average, a single photon per second (or less). This type of photon gun has the same problem as the other ones.
