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A crucial requirement for quantum information processing is the realization of multiple-qubit quantum gates. Here, we demonstrate an electron spin based all-electrical two-qubit gate consisting of single spin rotations and inter-dot spin…

Quantum Physics · Physics 2015-05-30 R. Brunner , Y. -S. Shin , T. Obata , M. Pioro-Ladrière , T. Kubo , K. Yoshida , T. Taniyama , Y. Tokura , S. Tarucha

We report the fabrication and characterization of a gate-defined double quantum dot formed in a Si/SiGe nanomembrane. In the past, all gate-defined quantum dots in Si/SiGe heterostructures were formed on top of strain-graded virtual…

The rich and electrostatically tunable phase diagram exhibited by moir\'e materials has made them a suitable platform for hosting single material multi-purpose devices. To engineer such devices, understanding electronic transport and…

This is a review on graphene quantum dots and their use as a host for spin qubits. We discuss the advantages but also the challenges to use graphene quantum dots for spin qubits as compared to the more standard materials like GaAs. We start…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 Patrik Recher , Bjoern Trauzettel

If a device like a graphene nanoribbon (GNR) has all its four corners attached to electric current leads, the device becomes a quantum junction through which two electrical circuits can interact. We study such system theoretically for…

Mesoscale and Nanoscale Physics · Physics 2017-12-21 Martin Konôpka , Peter Dieška

Probing techniques with spatial resolution have the potential to lead to a better understanding of the microscopic physical processes and to novel routes for manipulating nanostructures. We present scanning-gate images of a graphene quantum…

Mesoscale and Nanoscale Physics · Physics 2012-06-13 S. Schnez , J. Güttinger , M. Huefner , C. Stampfer , K. Ensslin , T. Ihn

Double quantum dot nanostructures embedded between two superconducting leads or in a superconducting ring have complex excitation spectra inside the gap which reveal the competition between different many-body phenomena. We study the…

Strongly Correlated Electrons · Physics 2017-10-02 Rok Zitko

We present low temperature transport measurements on double quantum dots in InAs nanowires grown by metal-organic vapor phase epitaxy. Two dots in series are created by lithographically defined top-gates with a procedure involving no extra…

Mesoscale and Nanoscale Physics · Physics 2015-06-25 A. Pfund , I. Shorubalko , R. Leturcq , K. Ensslin

We propose a quantum gate architecture that allows for the systematic control of the effective exchange interactions between magnetic impurities embedded in nano-scale graphene flakes connected by a gated bridge. The entanglement between…

Mesoscale and Nanoscale Physics · Physics 2021-09-06 Phillip Weinberg , Adrian E. Feiguin

We report the realization of nanotube-based quantum dot structures that use local electrostatic gating to produce individually controllable dots in series along a nanotube. Electrostatic top-gates produce depletion regions in the underlying…

Mesoscale and Nanoscale Physics · Physics 2015-06-25 M. J. Biercuk , S. Garaj , N. Mason , J. M. Chow , C. M. Marcus

We demonstrate theoretically that quantum dots in bilayers of graphene can be realized. A position-dependent doping breaks the equivalence between the upper and lower layer and lifts the degeneracy of the positive and negative momentum…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 J. Milton Pereira , P. Vasilopoulos , F. M. Peeters

The electronic states of an electrostatically confined cylindrical graphene quantum dot and the electric transport through this device are studied theoretically within the continuum Dirac-equation approximation and compared with numerical…

Mesoscale and Nanoscale Physics · Physics 2011-08-12 G. Pal , W. Apel , L. Schweitzer

Double quantum dots (DQDs) hold great promise as building blocks for quantum technology as they allow for two electronic states to coherently couple. Defining QDs with materials rather than using electrostatic gating allows for QDs with a…

Mesoscale and Nanoscale Physics · Physics 2021-09-08 David Barker , Sebastian Lehmann , Luna Namazi , Malin Nilsson , Claes Thelander , Kimberly A. Dick , Ville F. Maisi

Free standing beams containing a two-dimensional electron system are shaped from a GaAs/AlGaAs heterostructure. Quantum point contacts and (double) quantum dots are laterally defined using metal top gates. We investigate the electronic…

Mesoscale and Nanoscale Physics · Physics 2010-06-17 C Rossler , M Bichler , D Schuh , W Wegscheider , S Ludwig

Coulomb blockade is observed in a graphene nanoribbon device with a top gate. When two pn junctions are formed via the back gate and the local top gate, electrons are confined between the pn junctions which act as the barriers. When no pn…

Mesoscale and Nanoscale Physics · Physics 2009-12-11 Xinglan Liu , Jeroen B. Oostinga , Alberto F. Morpurgo , Lieven M. K. Vandersypen

We have developed an etching process to fabricate a quantum dot and a nearby single electron transistor as a charge detector in a single layer graphene. The high charge sensitivity of the detector is used to probe Coulomb diamonds as well…

Mesoscale and Nanoscale Physics · Physics 2015-05-19 Ling-Jun Wang , Gang Cao , Tao Tu , Hai-Ou Li , Cheng Zhou , Xiao-Jie Hao , Zhan Su , Guang-Can Guo , Guo-Ping Guo , Hong-Wen Jiang

At the center of quantum computing1 realization is the physical implementation of qubits - two-state quantum information units. The rise of graphene2 has opened a new door to the implementation. Because graphene electrons simulate…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 G. Y. Wu , N. -Y. Lue , L. Chang

We suggest a way of confining quasiparticles by an external potential in a small region of a graphene strip. Transversal electron motion plays a crucial role in this confinement. Properties of thus obtained graphene quantum dots are…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 P. G. Silvestrov , K. B. Efetov

Electrostatically defined quantum dots in bilayer graphene offer a promising platform for spin qubits with presumably long coherence times due to low spin-orbit coupling and low nuclear spin density. We demonstrate two different…

We study transport through a triple quantum dot in a triangular geometry with applied bias such that both singly- and doubly- charged states participate. We describe the formation of electronic dark states -- coherent superpositions that…

Mesoscale and Nanoscale Physics · Physics 2009-09-18 Christina Pöltl , Clive Emary , Tobias Brandes