@article{53d0a3bef9864be5acd84cae21814594,
title = "Exchange Coupling in a Linear Chain of Three Quantum-Dot Spin Qubits in Silicon",
abstract = "Quantum gates between spin qubits can be implemented leveraging the natural Heisenberg exchange interaction between two electrons in contact with each other. This interaction is controllable by electrically tailoring the overlap between electronic wave functions in quantum dot systems, as long as they occupy neighboring dots. An alternative route is the exploration of superexchange - the coupling between remote spins mediated by a third idle electron that bridges the distance between quantum dots. We experimentally demonstrate direct exchange coupling and provide evidence for second neighbor mediated superexchange in a linear array of three single-electron spin qubits in silicon, inferred from the electron spin resonance frequency spectra. We confirm theoretically, through atomistic modeling, that the device geometry only allows for sizable direct exchange coupling for neighboring dots, while next-nearest neighbor coupling cannot stem from the vanishingly small tail of the electronic wave function of the remote dots, and is only possible if mediated.",
keywords = "exchange interaction, qubit, silicon, superexchange",
author = "Chan, {Kok Wai} and Harshad Sahasrabudhe and Wister Huang and Yu Wang and Yang, {Henry C.} and Menno Veldhorst and Hwang, {Jason C.C.} and Mohiyaddin, {Fahd A.} and Hudson, {Fay E.} and Itoh, {Kohei M.} and Andre Saraiva and Andrea Morello and Arne Laucht and Rajib Rahman and Dzurak, {Andrew S.}",
note = "Funding Information: We acknowledge support from the U.S. Army Research Office (W911NF-17-1-0198), the Australian Research Council (FL190100167 and CE170100012), and the NSW Node of the Australian National Fabrication Facility. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Office or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. K.M.I. acknowledges support from a Grant-in-Aid for Scientific Research by MEXT, NanoQuine, FIRST, and the JSPS Core-to-Core Program. This research is part of the Blue Waters sustained-petascale computing project, which is supported by the National Science Foundation (Awards OCI-0725070 and ACI-1238993) and the state of Illinois. Blue Waters is a joint effort of the University of Illinois at Urbana–Champaign and its National Center for Supercomputing Applications. Publisher Copyright: {\textcopyright} 2021 American Chemical Society.",
year = "2021",
month = feb,
day = "10",
doi = "10.1021/acs.nanolett.0c04771",
language = "English",
volume = "21",
pages = "1517--1522",
journal = "Nano Letters",
issn = "1530-6984",
publisher = "American Chemical Society",
number = "3",
}