We demonstrate a new method for projective single-shot measurement of two electron spin states (singlet versus triplet) in an array of gate-defined lateral quantum dots in GaAs. The measurement has very high fidelity and is robust with respect to electric and magnetic fluctuations in the environment. It exploits a long-lived metastable charge state, which increases both the contrast and the duration of the charge signal distinguishing the two measurement outcomes. This method allows us to evaluate the charge measurement error and the spin-to-charge conversion error separately. We specify conditions under which this method can be used, and project its general applicability to scalable quantum dot arrays in GaAs or silicon.
@article{arxiv.1701.03622,
title = {Robust Single-Shot Spin Measurement with 99.5% Fidelity in a Quantum Dot Array},
author = {Takashi Nakajima and Matthieu R. Delbecq and Tomohiro Otsuka and Peter Stano and Shinichi Amaha and Jun Yoneda and Akito Noiri and Kento Kawasaki and Kenta Takeda and Giles Allison and Arne Ludwig and Andreas D. Wieck and Daniel Loss and Seigo Tarucha},
journal= {arXiv preprint arXiv:1701.03622},
year = {2017}
}