One of the radiation detectors with the best energy resolution are TES (Transition Edge Sensor), a quantum sensor based on the abrupt change in resistance in a superconductor when it transitions from normal state to superconducting state. Depending on the design and the absorber used, it can detect radiation of different energies. Our group has been developing these detectors for over 10 years for the X-ray range, specifically for ATHENA, a telescope that ESA will launch into space in the next decade. We are currently developing detectors in the UVOIR range (ultraviolet, visible and infrared), with applications in quantum communication and technologies, as well as in astronomy. The doctoral candidate would perform experimental work, joining the research team and participating both in the fabrication of devices in the clean room and in their characterization in a dilution refrigerator at very low temperatures (10 mK), including hardware control programming, analysis and simulation. In the case of X-rays, the doctoral candidate's objective will be to improve the current energy resolution of the detector. To achieve this, the candidate will need to improve the characterization setup and the detector design. In the case of optical detection, the efficiency of the absorbers will need to be improved and the detector response optimized. For all of this, they will have the support of an experienced team, as well as the necessary technical resources.