Internship: Inertial quantum sensing based on optomechanical coupling in rare-earth-doped crystals

Developing a broadband, high-sensitivity accelerometer operating at cryogenic temperatures is a key challenge in many cutting-edge experimental physics domains, from quantum technologies (including near-field microscopy, quantum memories, …) to gravitational wave detection. To realize such a sensor, a promising approach is hybrid optomechanics, which couples quantum and mechanical degrees of freedom in a single physical system.
Rare-earth ion-doped crystals, known for their extremely narrow optical transitions at low temperature (~3K), also exhibit intrinsic optomechanical coupling via the sensitivity of the ion’s energy levels to mechanical stress (see Figure). This is why these crystals have recently emerged as strong candidates for quantum-enabled, low-temperature accelerometry. We recently demonstrated continuous optical measurement of vibrations with such crystals, with already promising sensitivity and bandwidth [1,2]. However, significant work is still needed to obtain an ultra-sensitive, unidirectional and calibrated accelerometer.

During this internship, we will investigate the fundamental and technical limitations of the method (in terms of sensitivity and bandwidth in particular), using emulated or real vibrations. Additionally, we aim to extend the operational range to higher temperatures (up to 10K), which will be key for expanding the potential applications of our sensor.

Methods and techniques:

Spectral hole burning, stable lasers, closed-cycle cryostats.

Applicant profile:

background knowledge in one or several of the following fields: quantum mechanics, light-matter interaction, laser physics and/or condensed matter physics. A taste for experimental physics and teamwork is expected, as well as a good level of English. Basic programming skills are appreciated (e.g. Matlab).