Phonon-laser ultrasensitive force sensor

TL;DR

This paper demonstrates an ultrasensitive force detection method using a single trapped ion as a phonon laser, achieving detection sensitivities down to 86.5 yN with phase squeezing.

Contribution

It introduces a novel nano-sensor based on a single trapped ion with injection-locking and phase squeezing for ultrasensitive force measurement.

Findings

Force sensitivity of 347 ± 50 yN/√Hz achieved.

Enhanced sensitivity to 86.5 ± 70.1 yN with phase squeezing.

Stable ion trapping and phase synchronization demonstrated.

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 $\pm$ 50 yN/$\sqrt{Hz}$. Further with 3 dB squeezing applied on the oscillation phase variance, we achieved a successful detection of the smallest force to be 86.5 $\pm$ 70.1 yN.