Millikelvin temperatures testbed for future dark matter experiments with quantum-limited amplifiers.

At the low energy frontier of particle physics, experiments that test the validity of fundamental theories require detectors at the ultimate level of sensitivity allowed by quantum mechanics. In cavity-based searches of axion dark matter (DM), 3D resonators and the first stage of amplification of the receiver electronics, a Josephson parametric amplifier (JPA), are cooled down to ultra-cryogenic temperatures to minimize thermal noise. This is accomplished within dilution refrigerators, that are equipped with microwave components and devices that have to be carefully tested and characterised in order to assess the noise introduced by the receiver. This thesis presents the characterisation and optimization of a receiver chain operated in the new dilution refrigerator available at LNL INFN laboratories that will be used for future DM searches. I will also describe in detail how it was equipped with all the necessary RF components to run the receivers tests while not impacting on the base temperature, i.e. about 7 mK, reached during commissioning.