We demonstrate high-fidelity Zeeman qubit state detection in a single trapped 88 Sr+ ion. Qubit readout is performed by shelving one of the qubit states to a metastable level using a narrow linewidth diode laser at 674 nm followed by state-selective fluorescence detection. The average fidelity reached for the readout of the qubit state is 0.9989(1). We then measure the fidelity of state tomography, averaged over all possible single-qubit states, which is 0.9979(2). We also fully characterize the detection process using quantum process tomography. This readout fidelity is compatible with recent estimates of the detection error-threshold required for fault-tolerant computation, whereas high-fidelity state tomography opens the way for high-precision quantum process tomography.
@article{arxiv.1103.5253,
title = {High-fidelity state detection and tomography of a single ion Zeeman qubit},
author = {Anna Keselman and Yinnon Glickman and Nitzan Akerman and Shlomi Kotler and Roee Ozeri},
journal= {arXiv preprint arXiv:1103.5253},
year = {2013}
}