Coupled electron spins in semiconductor double quantum dots hold promise as the basis for solid-state qubits. To date, most experiments have used III-V materials, in which coherence is limited by hyperfine interactions. Ge/Si heterostructure nanowires seem ideally suited to overcome this limitation: the predominance of spin-zero nuclei suppresses the hyperfine interaction and chemical synthesis creates a clean and defect-free system with highly controllable properties. Here we present a top gate-defined double quantum dot based on Ge/Si heterostructure nanowires with fully tunable coupling between the dots and to the leads. We also demonstrate a novel approach to charge sensing in a one-dimensional nanostructure by capacitively coupling the double dot to a single dot on an adjacent nanowire. The double quantum dot and integrated charge sensor serve as an essential building block required to form a solid-state spin qubit free of nuclear spin.
@article{arxiv.0706.2271,
title = {Double quantum dot with integrated charge sensor based on Ge/Si heterostructure nanowires},
author = {Yongjie Hu and Hugh H. O. Churchill and David J. Reilly and Jie Xiang and Charles M. Lieber and Charles M. Marcus},
journal= {arXiv preprint arXiv:0706.2271},
year = {2015}
}