Phonon-laser ultrasensitive force sensor

Abstract

Developing nano-mechanical oscillators for ultrasensitive force detection is of great importance in exploring science. We report our achievement of ultrasensitive detection of the external force regarding the radio-frequency electric field by a nano-sensor made of a single trapped 40 Ca + ion under injection-locking, where squeezing is additionally applied to detection of the smallest force in the ion trap. The employed ion is confined stably in a surface electrode trap and works as a phonon laser that is very sensitive to the external disturbance. The injection-locking drove the ion's oscillation with phase synchronization, yielding the force detection with sensitivity of 347 ± 50 yN/ √ Hz. Further with 3 dB squeezing applied on the oscillation phase variance, we achieved a successful detection of the smallest force to be 86.5 ± 70.1 yN.