The Standard Model of particle physics was completed by discovery of the Higgs boson in 2012. This model beautifully explains most of the experimental facts but does contradict with some important exceptions. One of the major issues of particle physics is lack of dark matter candidates in its present form, and therefore, lots of possible extensions beyond the Standard Model have been proposed, including super string theory. Such extensions naturally predict new particles which may very weakly interact with the ordinary particles in the Standard Model. Some of them can be dark matter candidates. Since an ordinary photon may couple with such hypothetical particles, new photon technology, in particular above 30 GHz, is a key to address such particles in unexplored parameter regions. In this colloquium, general introduction of this research field of particle physics will be presented, followed by two specific projects related to gyrotrons, originally developed for plasma heating and nuclear fusion. First, we will discuss precision measurement of atomic levels of positronium, a bound state of electron and position, by using gyrotrons. Secondly, direct search for new massive gauge bosons, often referred to as dark photons, with gyrotrons of frequency higher than 30 GHz, will be proposed. The latter project is under the preliminary consideration with Karlsruhe Institute for Technology to use their R&D gyrotron. In these applications for particle physics, a crucial engineering aspect is the ultimate frequency stability of gyrotrons with for example phase-lock loop and injection locking techniques. The impact of these new techniques to the fundamental physics will be described. Furthermore, ultimate limitation of classical electrodynamics for photon detection will be introduced with its remedy with superconducting quantum sensors, which is a hot topic in the particle physics community with a link to quantum computing technology.
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