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Stacking two layers of graphene with atomic layer thickness produces bilayer graphene, which possesses excellent electrical, mechanical, and optical properties. As such, bilayer graphene has attracted significant attention and is being utilized in a host of next-generation devices, including quantum computers. But complicating their application in quantum computing comes in the form of gaining accurate measurements of the quantum bit states. Most research has primarily used low-frequency electronics to overcome this. However, for applications that demand faster electronic measurements and insights into the rapid dynamics of electronic states, the need for quicker and more sensitive measurement tools has become evident. Now, a group of researchers from Tohoku University have outlined improvements to radio-frequency (rf) reflectometry to achieve a high-speed readout technique. Remarkably, the breakthrough involves the use of graphene itself. (a) The layer structure of the fabricated device. (b) The resonant circuit used for rf-reflectometry. ©Tomoya Johmen et al. Rf reflectometry works by sending radio frequency signals into a transmission line and then measuring the reflected signals to obtain information about samples. But in devices employing bilayer graphene, the presence of significant stray capacitance in the measurement circuit leads to rf leakage and less-than-optimal resonator properties. Whilst various techniques have been explored to mitigate this, clear device design guidelines are still awaited. The dependence of rf reflection characteristics on gate voltage, showing the change in conductance. ©Tomoya Johmen et al. “To circumvent this common shortfall of rf reflectometry in bilayer graphene, we employed a microscale graphite back-gate and an undoped silicon substrate,” says Tomohiro Otsuka, corresponding author of the paper and associate professor at Tohoku University’s Advanced Institute for Materials Research (WPI-AIMR). “We successfully realized good rf matching conditions, calculated the readout accuracy numerically, and compared these measurements with direct current measurements to confirm its consistency. This allowed us to observe Coulomb diamonds through rf reflectometry, a phenomenon indicating the formation of quantum dots in the conduction channel, driven by potential fluctuations caused by bubbles.” Coulomb diamonds originating from the formation of quantum dots are observed by monitoring the reflected voltage from the resonator. ©Tomoya Johmen et al. Otsuka and his team’s proposed improvements to rf reflectometry provide important contributions to the development of next-generation devices such as quantum computers, and the exploration of physical properties using two-dimensional materials, such as graphene. The details of their study were reported in the journal Physical Review Applied. Publication Details: Title: Radio-Frequency Reflectometry in Bilayer Graphene Devices Utilizing Microscale Graphite Back-Gates Authors: Tomoya Johmen, Motoya Shinozaki, Yoshihiro Fujiwara, Takumi Aizawa, and Tomohiro Otsuka Journal: Physical Review Applied DOI: 10.1103/PhysRevApplied.20.014035 Contact Division of Public Relations School of Engineering, Tohoku University E-mail:[email protected] News NewsNews ListAnnouncementsPressreleaseResearchAwardsVacancies   Top of the page Contact Sitemap Emergency Information Undergraduate Departments Mechanical and Aerospace Engineering Electrical, Information and Physics Engineering Applied Chemistry, Chemical Engineering and Biomolecular Engineering Materials Science and Engineering Civil Engineering and Architecture Graduate Departments Mechanical Systems Engineering Finemechanics Robotics Aerospace Engineering Quantum Science and Energy Engineering Electrical Engineering Communications Engineering Electronic Engineering Applied Physics Applied Chemistry Chemical Engineering Biomolecular Engineering Metallurgy Materials Science Materials Processing Civil and Environmental Engineering Architecture and Building Science Management Science and Technology Affiliated Educational and Research Facilities Fracture and Reliability Research Institute(FRRI) Research Center of Supercritical Fluid Terchnolody Micro/Nano-Machining Research and Education Center Innovation Plaza International Office (EngIO) Technical Division Tohoku University Engineering Library School of Engineering, Tohoku University 6-6, Aramaki Aza Aoba, Aoba-ku, Sendai, Miyagi 980-8579, Japan © School of Engineering, Tohoku University Japanese About Us Message from the DeanEducational GoalUndergraduateGraduateResearch Purposes and ObjectivesHistoryFiguresAcademic and Other StaffStudentsInternational StudentsRevenueCareer PathsUndergraduateGraduateBrochuresNewsLetter Departments Departments Academics Field of StudyGraduateUndergraduateUndergraduate ProgramsMaster&＃039;s ProgramsDoctoral ProgramsExchange ProgramsResearch Student Admissions Programs and ApplicationApplication ProceduresUndergraduate ProgramsMaster&＃039;s ProgramsDoctoral ProgramsResearch StudentExchange ProgramsTuition and Other Fees International Affairs Scholarships and FundsEventsHandbook for International Students International Support Office(TU Support)Entry into Japansummer-programOfficesWork under Student VisaExtension of Period of Stay or Change of StatusHousingTutor SystemWaiver of FeesRequired Insurance for All International Students of Engineering SchoolCounseling Services in School of EngineeringHealthcare RoomJapanese Language ClassesStatus of residence when taking a leave of absenceSeeking employment after graduationStatus of Residence after Leaving Tohoku University Research PressreleaseTUNE News News List Announcements Pressrelease Vacancies Awards Emergenccy Access パンフレット・出版物 --> Campus Map Direction Contact Sitemap 関連サイトへのリンク 情報公開 Site Policy --> Tohoku University no cache