This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:

fact-checked

peer-reviewed publication

trusted source

proofread

Researchers demonstrate a high-speed electrical readout method for graphene nanodevices

Researchers demonstrate a high-speed electrical readout method for graphene nanodevices
(a) The layer structure of the fabricated device. (b) The resonant circuit used for rf-reflectometry. Credit: Tomoya Johmen et al.

Graphene is well-known for its high electrical conductivity, mechanical strength, and flexibility. 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 a complication to their application in 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 (rf) reflectometry to achieve a high-speed readout technique. Remarkably, the breakthrough involves the use of itself. The details of their study were reported in the journal Physical Review Applied.

Rf reflectometry works by sending radio frequency signals into a and then measuring the reflected signals to obtain information about samples. But in devices employing , the presence of significant stray capacitance in the measurement circuit leads to rf leakage and less-than-optimal resonator properties. While various techniques have been explored to mitigate this, clear device design guidelines are still awaited.

  • Researchers demonstrate a high-speed electrical readout method for graphene nanodevices
    The dependence of rf reflection characteristics on gate voltage, showing the change in conductance. Credit: Tomoya Johmen et al.
  • Researchers demonstrate a high-speed electrical readout method for graphene nanodevices
    Coulomb diamonds originating from the formation of quantum dots are observed by monitoring the reflected voltage from the resonator. Credit: 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."

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.

More information: Tomoya Johmen et al, Radio-Frequency Reflectometry in Bilayer Graphene Devices Utilizing Microscale Graphite Back-Gates, Physical Review Applied (2023). DOI: 10.1103/PhysRevApplied.20.014035

Journal information: Physical Review Applied

Provided by Tohoku University

Citation: Researchers demonstrate a high-speed electrical readout method for graphene nanodevices (2023, October 20) retrieved 1 March 2024 from https://phys.org/news/2023-10-high-speed-electrical-readout-method-graphene.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Explore further

Physicists unlock controllable nonlinear Hall effect in twisted bilayer graphene

8 shares

Feedback to editors