High-Sensitivity Accelerometry with a Feedback-Cooled Magnetically Levitated Microsphere

We show that a magnetically levitated microsphere in high vacuum can be used as an accelerometer by comparing its response to of commercially available geophone. This system shows great promise for ultrahigh acceleration sensitivities without the need large masses or cryogenics. With feedback cooling, transient decay time is reduced and center-of-mass motion cooled 9 K less. Remarkably, levitated-particle has sensitivity down $3.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}\phantom{\rule{0.2em}{0ex}}\mathrm{g}/\sqrt{\mathrm{Hz}}$ gives measurements similar those commercial geophone at frequencies up 14 Hz despite test mass four billion times smaller. no free parameters calibration, responses accelerometers match within 3% 5 Hz. The reaches this due relatively particle $0.25\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{g}$, low oscillation frequency 1.75 Hz, image-analysis method measure displacement with uncertainty 1.6 nm single image.