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Sensitive charge detection has enabled qubit readout in solid-state systems. Recently, an alternative to the well-established charge detection via on-chip electrometers has emerged, based on in situ gate detectors and radio-frequency…

Mesoscale and Nanoscale Physics · Physics 2017-05-24 A. Rossi , R. Zhao , A. S. Dzurak , M. F. Gonzalez-Zalba

We present a highly controllable double quantum dot device based on bilayer graphene. Using a device architecture of interdigitated gate fingers, we can control the interdot tunnel coupling between 1 to 4 GHz and the mutual capacitive…

We propose to continuously monitor a charge qubit by utilizing a T-shaped double quantum dot detector, in which the qubit and double dot are arranged in such a unique way that the detector turns out to be particularly susceptible to the…

Mesoscale and Nanoscale Physics · Physics 2015-01-16 JunYan Luo , HuJun Jiao , Jing Hu , Xiao-Ling He , XiaoLi Lang , Shi-Kuan Wang

The electrostatic confinement of massless charge carriers is hampered by Klein tunneling. Circumventing this problem in graphene mainly relies on carving out nanostructures or applying electric displacement fields to open a band gap in…

We report the dispersive charge-state readout of a double quantum dot in the few-electron regime using the in situ gate electrodes as sensitive detectors. We benchmark this gate-sensing technique against the well established quantum point…

Mesoscale and Nanoscale Physics · Physics 2015-09-24 J. I. Colless , A. C. Mahoney , J. M. Hornibrook , A. C. Doherty , D. J. Reilly , H. Lu , A. C. Gossard

Single electron charging in an individual InAs quantum dot was observed by electrostatic force measurements with an atomic force microscope (AFM). The resonant frequency shift and the dissipated energy of an oscillating AFM cantilever were…

Laterally coupled charge sensing of quantum dots is highly desirable, because it enables measurement even when conduction through the quantum dot itself is suppressed. In this work, we demonstrate such charge sensing in a double top gated…

We experimentally investigate the charge induction mechanism across gated, narrow, ballistic graphene devices with different degrees of edge disorder. By using magnetoconductance measurements as the probing technique, we demonstrate that…

Graphene quantum dots (QDs) are intensively studied as platforms for the next generation of quantum electronic devices. Fine tuning of the transport properties in monolayer graphene QDs, in particular with respect to the independent…

Time-resolved electron dynamics in coupled quantum dots is directly observed by a pulsed-gate technique. While individual gate voltages are modulated with periodic pulse trains, average charge occupations are measured with a nearby quantum…

Mesoscale and Nanoscale Physics · Physics 2010-11-12 D. Harbusch , S. Manus , H. P. Tranitz , W. Wegscheider , S. Ludwig

In order to employ solid state quantum dots as qubits, both a high degree of control over the confinement potential as well as sensitive charge detection are essential. We demonstrate that by combining local anodic oxidation with local…

Mesoscale and Nanoscale Physics · Physics 2011-06-13 C. Rössler , B. Küng , S. Dröscher , T. Choi , T. Ihn , K. Ensslin , M. Beck

Nanostructures defined in high-mobility two-dimensional electron systems offer a unique way of controlling the microscopic details of the investigated device. Quantum point contacts play a key role in these investigations, since they are…

Mesoscale and Nanoscale Physics · Physics 2014-03-19 Clemens Rössler , Tobias Krähenmann , Stephan Baer , Thomas Ihn , Klaus Ensslin , Christian Reichl , Werner Wegscheider

We report charge sensing measurements on a silicon quantum dot (QD) with a nearby silicon single electron transistor (SET) acting as an electrometer. The devices are electrostatically formed in bulk silicon using surface gates. We show that…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 G. J. Podd , S. J. Angus , D. A. Williams , A. J. Ferguson

Bilayer graphene is a nanomaterial that allows for well-defined, separated quantum states to be defined by electrostatic gating and, therefore, provides an attractive platform to construct tunable quantum dots. When a magnetic field…

Mesoscale and Nanoscale Physics · Physics 2022-12-23 Jozef Bucko , Frank Schäfer , František Herman , Rebekka Garreis , Chuyao Tong , Annika Kurzmann , Thomas Ihn , Eliska Greplova

We provide a physical analysis of the charging and detection of the first few electrons in a laterally-coupled GaAs/AlGaAs quantum dot (LCQD) circuit with integrated quantum point contact (QPC) read-out. Our analysis is based on the…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 L. -X. Zhang , P. Matagne , J. P. Leburton , R. Hanson , L. P. Kouwenhoven

A quantum dot has been etched in bilayer graphene connected by two small constrictions to the leads. We show that this structure does not behave like a single quantum dot but consists of at least three sites of localized charge in series.…

Mesoscale and Nanoscale Physics · Physics 2014-06-23 Dominik Bischoff , Anastasia Varlet , Pauline Simonet , Thomas Ihn , Klaus Ensslin

We use an on-chip superconducting resonator as a sensitive meter to probe the properties of graphene double quantum dots at microwave frequencies. Specifically, we investigate the charge dephasing rates in a circuit quantum electrodynamics…

We present transport measurements on a strongly coupled graphene quantum dot in a perpendicular magnetic field. The device consists of an etched single-layer graphene flake with two narrow constrictions separating a 140 nm diameter island…

Mesoscale and Nanoscale Physics · Physics 2011-05-03 J. Guettinger , C. Stampfer , T. Frey , T. Ihn , K. Ensslin

It is known that a quantum computer operating on electron-spin qubits with single-electron Hamiltonians and assisted by single-spin measurements can be simulated efficiently on a classical computer. We show that the exponential speed-up of…

Quantum Physics · Physics 2007-05-23 C. W. J. Beenakker , D. P. DiVincenzo , C. Emary , M. Kindermann

We report integrated charge sensing measurements on a Si/SiGe double quantum dot. The quantum dot is shown to be tunable from a single, large dot to a well-isolated double dot. Charge sensing measurements enable the extraction of the tunnel…