Shot-noise limited monitoring and phase locking of the motion of a single trapped ion

TL;DR

This paper demonstrates shot-noise limited, high-resolution real-time monitoring and phase locking of a single trapped ion's motion, achieving measurement precision below the standard quantum limit through interferometry and feedback control.

Contribution

It introduces a method for shot-noise limited measurement and phase locking of a single ion's motion, enhancing measurement precision beyond the standard quantum limit.

Findings

Achieved measurement resolution of 4 times the standard quantum limit.

Successfully implemented phase locking to suppress phase diffusion.

Measured coherent ion oscillations with 0.3 times the standard quantum limit.

Abstract

We perform high-resolution real-time read-out of the motion of a single trapped and laser-cooled Ba ion. By using an interferometric setup we demonstrate shot-noise limited measurement of thermal oscillations with resolution of 4 times the standard quantum limit. We apply the real-time monitoring for phase control of the ion motion through a feedback loop, suppressing the photon recoil-induced phase diffusion. Due to the spectral narrowing in phase-locked mode, the coherent ion oscillation is measured with resolution of about 0.3 times the standard quantum limit.