Quantum cavity optoacoustics at room temperature using a cm-scale crystal

Cavity optomechanics is a field that investigates the interaction between photons and phonons in optomechanical cavities, offering insights into fundamental physics and potential applications in quantum technologies. This master thesis focuses on the exploration of the strong-coupling regime in a macroscopic system operating at room temperature, utilizing a centimeter-scale quartz crystal enclosed within an optical resonator capable of sustaining high-frequency bulk acoustic waves at approximately 12.5 GHz. The Brillouin optomechanical interactions couple the light to the mechanical system and, when the phenomenon is in resonance with the optical cavity modes, enable transferring of power between them, i.e., optomechanically induced amplification (OMIA) and transparency (OMIT). Operating at room temperature presents several advantages, including the ability to thermally tune the cavity resonances and employ high-power optical beams (∼ 100 mW). These conditions enable the achievement of the strong-coupling regime with an effective photon coupling rate in the MHz range. In this regime, the confinement and intrinsic losses of the optical and acoustic modes are overcome by the light coupled from the optical pump and create hybrid optoacoustic modes. The results of this work serve as essential prerequisites for investigating Brillouin interactions at cryogenic temperatures and enabling the development of hybrid quantum technologies, such as quantum memories and microwave-to-optical transducers.