Speaker
Description
Levitated mechanical resonators have the potential to achieve low mechanical loss and high quality factor (Q factor), which is critical for many applications, e.g. high precision sensors, and exploring fundamental quantum physics. Diamagnetic levitation is a promising technique that requires no energy input and can trap massive objects. However, conductive pyrolytic graphite, one of the strongest room-temperature diamagnetic materials, suffers severe eddy damping, leading to a very low Q factor. We explored different methods to increase the Q factor to satisfy a variety of applications. Firstly, we cut slots into the graphite plate to interrupt the eddy currents and the Q is increased by a factor of ∼ 40 while keeping the integrity of the plate itself. In the second method, we make insulating composites by blending the insulating-coated graphite powders with vacuum-compatible wax. The cm-sized composite resonators achieve a motional Q factor at the scale of 10^5. We also cool the center-of-mass motion of the composite resonator by 3 orders of magnitude, using the feedback method. In addition, we demonstrate that when a diamagnetic conducting rotor is levitated in an axially symmetric magnetic field, its rotational motion can, in principle, evade eddy current damping entirely. These low-mechanical-loss resonators provide ideal platforms to build ultraprecise sensors, e.g., gravimeters, and study macroscopic quantum states for exploring quantum gravity.