Expérimental
The realization of a cryogenic, broadband, high-sensitivity accelerometer is a major challenge in many physics domains, from quantum technologies to seismology and gravitational wave detection. In rare-earth ion-doped crystals, well known for their very narrow optical transitions at low temperatures, and increasingly used in quantum technologies, the energy levels are coupled to the mechanical stress of the host matrix via the crystal field around the ion. We have recently demonstrated that this coupling can be exploited to provide a continuous optical measurement of the mechanical vibrations of a cryostat, with an already promising sensitivity and bandwidth. This measurement is based on the continuous interrogation of the optical transition with a monochromatic laser. The internship will consist in pushing the development of this sensor to achieve an ultra-sensitive, unidirectional and calibrated accelerometer.