Dynamics of levitated nanoparticles in high vacuum
This event is part of the Biophysics/Condensed Matter Seminar Series.
Abstract: Nano- and micromechanical oscillators with high quality (Q) factors have gained much attention for their potential application in sensing, signal processing and transduction, and for fundamental research aiming at observing quantum mechanical behavior in macroscopic systems. In particular in the context of macroscopic quantum mechanics and force sensing, levitated nanoparticles are very attractive because of their exceptionally high Q-factor and very low mass.
For an optically levitated nanoparticle in high vacuum, we observe Q-factors exceeding 10^8. The ultra-high Q-factor together with the tiny mass of the nanoparticle offers an unprecedented force sensitivity in the zepto-Newton range at room temperature. This would be sufficient to sense ultra-weak interactions, such as non-Newtonian gravity-like forces and tiny forces arising from quantum vacuum fluctuations. Here, we find that a levitated nanoparticle is so sensitive that already collisions with much lighter residual air molecules suffice to drive the motion of the nanoparticle into the nonlinear regime. Using a parametric feedback scheme, we cool the particle motion into a very low entropy state corresponding to an effective milli-Kelvin bath. In addition, we exploit our ability to produce low entropy states to experimentally test non-equilibrium fluctuation relations.