Measuring Vibrational Movements of Levitated Pyrolytic Graphite with a 10 GHz Microwave Cavity

Highly isolated mechanical oscillator systems with high quality-factors have profound applications in both sensing applications and quantum physics. The use of a material's diamagnetic response to achieve levitation is often overlooked as a means of creating this sort of isolated system. We present results for magnetically levitated pyrolytic graphite slabs within a microwave cavity. The motion of the pyrolytic graphite slab perturbs the resonant microwave mode which can be monitored to quantify the vibrational activity of the slab. This serves as a low-impact method of sensing the particle's movement and additionally allows for applications in cavity electro-mechanics. Acoustic measurements of a levitating 1mg slab of pyrolytic graphite in the 10 – 50 Hz frequency range utilizing a λ/4 coaxial microwave cavity with 10 GHz resonance are presented. These cavity measurements are compared to object tracking in slow motion video and results by other researchers on the rigid body dynamics of this levitated pyrolytic graphite system. [X. Chen, A. Keskekler, F. Alijani, and P. G. Steeneken, Appl. Phys. Lett. 116, 243505 (2020)]