Scalable quantum technologies will require an unprecedented combination of precision and complexity for designing stable structures of well-controllable quantum systems. It is a challenging task to find a suitable elementary building block, of which a quantum network can be comprised in a scalable way. Here we present the working principle of such a basic unit, engineered using molecular chemistry, whose control and readout are executed using a nitrogen vacancy (NV) center in diamond. The basic unit we investigate is a synthetic polyproline with electron spins localized on attached molecular sidegroups separated by a few nanometers. We demonstrate the readout and coherent manipulation of very few (≤6) of these S=1/2 electronic spin systems and access their direct dipolar coupling tensor. Our results show, that it is feasible to use spin-labeled peptides as a resource for a molecular-qubit based network, while at the same time providing simple optical readout of single quantum states through NV-magnetometry. This work lays the foundation for building arbitrary quantum networks using well-established chemistry methods, which has many applications ranging from mapping distances in single molecules to quantum information processing.
@article{arxiv.1703.08248,
title = {Molecular quantum spin network controlled by a single qubit},
author = {Lukas Schlipf and Thomas Oeckinghaus and Kebiao Xu and Durga Bhaktavatsala Rao Dasari and Andrea Zappe and Felipe Fávaro de Oliveira and Bastian Kern and Mykhailo Azarkh and Malte Drescher and Markus Ternes and Klaus Kern and Jörg Wrachtrup and Amit Finkler},
journal= {arXiv preprint arXiv:1703.08248},
year = {2017}
}