A simple free-space optics recipe for the generation and detection of the optical vortices superposition is demonstrated. For the purpose a doughnut laser beam is produced by the cracked glass plate. To control the vorticity of produced doughnut light, one can deform the cracked plate. For the generation of the optical vortices superposition and determination the vorticity of the produced doughnut light, two simple interferometry setups are employed. The experimental Sagnac interferometry setup for preparing and analysing superpositions of an optical vortex and Gaussian modes is presented. Furthermore, the superpositions of two twisted beam with the opposite topological charge numbers by an experimental Michelson-Sagnac interferometry is proposed. These simple free-space experiments are useful to the application of orbital angular momenta superpositions in the quantum cryptography and the undergraduate educations
In this paper, we have fabricated two quantum random number generators (QRNGs) based on different mechanisms. The first one is based on the photon time of arrival and produces high-quality random numbers without the need for post-processing but using expensive equipment. The second one is based on the tunneling effect in a Zener diode and produces random strings with comparable quality but using low-cost equipment. We then evaluated the random sequences from these QRNGs using a set of statistical tests and showed that they are suitable for special applications such as quantum technologies.
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