We propose an implementation of a singlet-only spin qubit in a GaAs-based triple quantum dot with a (1,4,1) charge occupation. In the central multi-electron dot, the interplay between Coulomb interaction and an out-of-plane magnetic field creates an energy spectrum with a tunable singlet-triplet splitting, which can be exploited to create a six-particle singlet-only qubit with a qubit splitting that can straightforwardly be tuned over tens of μeV by adjusting the external magnetic field. We confirm the full exchange-based electric control of the qubit and demonstrate its superior coherence properties due to its singlet-only nature.
@article{arxiv.1911.08345,
title = {Highly tunable exchange-only singlet-only qubit in a GaAs triple quantum dot},
author = {Arnau Sala and Jørgen Holme Qvist and Jeroen Danon},
journal= {arXiv preprint arXiv:1911.08345},
year = {2020}
}