Measurement-based cooling is a method by which a quantum system, initially in a thermal state, can be prepared in its ground state through some sort of measurement. This is done by making a measurement that heralds the system being in the desired state. Here we demonstrate the application of a measurement-based cooling technique to a trapped atomic ion. The ion is pre-cooled by Doppler laser cooling to a thermal state with a mean excitation of nˉ≈18 and the measurement-based cooling technique selects those occasions when the ion happens to be in the motional ground state. The fidelity of the heralding process is greater than 95%. This technique can be applied to other systems that are not as amenable to laser cooling as trapped ions.
@article{arxiv.2208.05332,
title = {Measurement-based ground state cooling of a trapped ion oscillator},
author = {Chungsun Lee and Simon C. Webster and Jacopo Mosca Toba and Ollie Corfield and George Porter and Richard C. Thompson},
journal= {arXiv preprint arXiv:2208.05332},
year = {2023}
}