Graphene amplifier may tap into the "terahertz gap"

Researchers from Loughborough University have created a unique graphene-based device which may unlock the elusive terahertz wavelengths and make revolutionary new technologies possible.

Graphene amplifier for the terahertz gap imageLight in the THz frequencies hits the ‘sandwich’ and is reflected with additional energy. Credit: Loughborough University

Terahertz waves (THz) are located between microwaves and infrared in the light frequency spectrum, but due to their low energy, scientists have been unable to harness their potential. This issue is known as the "terahertz gap".

Transparent graphene photodetectors enable advanced 3D camera

A team of researchers at the University of Michigan, led by Zhaohui Zhong, Jeffrey Fessler and Theodore Norris of the Department of Electrical Engineering and Computer Science, has created a 3D camera made from a stack of transparent graphene photodetectors that can capture and focus on objects that are different distances away from the camera lens. The device might find use in applications as diverse as biological imaging, driverless cars and robotics.

Objects at different distances from the lens will come into focus at different points inside the camera imageImage credit: Stephen Alvey, University of Michigan

Most of today’s optical imaging systems use a flat optical detector to record the intensity of light reflected from an object at each pixel. However, since these systems detect light in only one plane, all the information concerning the direction of the light rays is lost. This means that the recorded images are simple 2D projections of the actual 3D object being imaged.

Graphene shows excellent resistance to stress

Researchers from the University of Toronto have shown that graphene is highly resistant to fatigue and is able to withstand more than a billion cycles of high stress before it breaks.

The intrinsic strength of graphene has been measured at more than 100 gigapascals, among the highest values recorded for any material. But materials don't always fail because the load exceeds their maximum strength. Stresses that are small but repetitive can weaken materials by causing microscopic dislocations and fractures that slowly accumulate over time, a process known as fatigue.

NIST-led team uses graphene to create and image coupled quantum dots

Researchers at the National Institute of Standards and Technology (NIST) and their colleagues have used graphene and STM technology to create and image a novel pair of quantum dots — tiny islands of confined electric charge that act like interacting artificial atoms. Such “coupled” quantum dots could serve as a robust quantum bit, or qubit, the fundamental unit of information for a quantum computer. Moreover, the patterns of electric charge in the island can’t be fully explained by current models of quantum physics, offering an opportunity to investigate rich new physical phenomena in materials.

Graphene aids in imaging qubits imagea system of coupled quantum dots taken by STM shows electrons orbiting within two concentric sets of rings, separated by a gap. The inner set of rings represents one quantum dot; the outer, brighter set represents a larger, outer quantum dot. Credit: NIST

The NIST -led team included researchers from the University of Maryland NanoCenter and the National Institute for Materials Science in Japan. The team used the ultrasharp tip of a scanning tunneling microscope (STM) as if it were a stylus of sorts. Hovering the tip above an ultracold sheet of graphene, the researchers briefly increased the voltage of the tip.

German researchers examine how proximity affects the resistance of graphene

A research team from the University of Göttingen, together with the Chemnitz University of Technology and the Physikalisch-Technische Bundesanstalt Braunschweig, has investigated the influence of the crystal on which graphene is grown, on the electrical resistance of the resulting material.

Contrary to previous assumptions, the new results show that the process known as the ‘proximity effect’ varies considerably at a nanometre scale. To determine the electrical resistance of graphene at the smallest scale possible, the physicists used a scanning tunneling microscope (STM).

Versarien - Think you know graphene? Think again! Versarien - Think you know graphene? Think again!