Continuous quantum measurement and phase locking of a single trapped ion
Pavel A. Bushev, Gabriel Hetet, L. Slodička, D. Rotter, Mark A. Wilson, Ferdinand Schmidt‐Kaler, Jürgen Eschner, R. Blatt · arXiv (Cornell University) · 2012
We perform high-resolution real time read-out of the quantum 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 also realize quantum limited phase control of the ion motion, suppressing the photon recoil-induced phase diffusion through a feedback loop. 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.