Can a mechanical resonator oscillating at low frequency be prepared in its quantum ground state? This project explores hybrid quantum systems combining high-Q micromechanical resonators, optical readout and superconducting circuits, with the aim of probing and controlling the quantum motion of massive objects. The internship will focus first on the optical characterization of microfabricated silicon-nitride membranes and ribbons, patterned or unpatterned. Using digital holographic microscopy and laser interferometry, the student will map mechanical mode shapes and measure resonance frequencies, thermal motion and quality factors. Finite-element simulations will help select resonators for quantum experiments. A second stage will address coupling selected devices to superconducting circuits and performing microwave measurements in a dilution refrigerator near 10 mK. Superconducting qubits and electromechanical interactions provide tools to probe and control motion at the single-phonon level. The internship can lead to an ANR GRAVITATION-funded PhD targeting the quantum ground state of a high-Q mechanical mode at low frequency. The strategy is to prepare the mode near its ground state and dynamically tune its frequency through mechanical stress control. Preserving quantum coherence during this process is a central challenge, with prospects for quantum sensing and experiments at the interface between quantum physics and gravity.