Detecting extremely small forces helps exploring new physics quantitatively.
Here we demonstrate that the phonon laser made of a single trapped
40Ca+ ion behaves as an exquisite sensor for small force measurement.
We report our successful detection of small electric forces regarding the DC
trapping potential with sensitivity of 2.41±0.49 zN/Hz​, with
the ion only under Doppler cooling, based on the injection-locking of the
oscillation phase of the phonon laser in addition to the classical squeezing
applied to suppress the measurement uncertainty. We anticipate that such a
single-ion sensor would reach a much better force detection sensitivity in the
future once the trapping system is further improved and the fluorescence
collection efficiency is further enhanced.Comment: arXiv admin note: text overlap with arXiv:2110.0114