A new study led by DAI Qing’s team from the National Center for Nanoscience and Technology (NCNST) of the Chinese Academy of Sciences (CAS) and Javier Abajo from the Institute of Photonic Sciences (ICFO) in Spain has shown a gate-tunable nanoscale negative refraction of polaritons in the mid-infrared range through a van der Waals heterostructure of graphene and molybdenum trioxide. The atomically thick heterostructures weaken scattering losses at the interface while enabling an actively tunable transition of normal to negative refraction through electrical gating.
The work was published in Science (“Gate-tunable negative refraction of mid-infrared polaritons”).
Basic principle of the “polariton transistor”. The van der Waals heterostructure is constructed by decorating graphene on the molybdenum trioxide, and the antenna stimulates the polariton to transmit through the interface to form negative refraction. (Image: DAI Qing et al.)
A team led by Professor Andrea Morello has just demonstrated the operation of a new type of quantum bit, called ‘flip-flop’ qubit, which combines the exquisite quantum properties of single atoms, with easy controllability using electric signals, just as those used in ordinary computer chips.
“Sometimes new qubits, or new modes of operations, are discovered by lucky accident. But this one was completely by design,” says Prof. Morello. “Our group has had excellent qubits for a decade, but we wanted something that could be controlled electrically, for maximum ease of operation. So we had to invent something completely new.”
Prof. Morello’s group was the first in the world to demonstrate that using the spin of an electron as well as the nuclear spin of a single phosphorus atom in silicon could be used as ‘qubits’ – units of information that are used to make quantum computing calculations. He explains that while both qubits perform exceptionally well on their own, they require oscillating magnetic fields for their operation.
Imagine you’re a young engineer whose boss drops by one morning with a sheaf of complicated fluid dynamics equations. “We need you to design a system to solve these equations for the latest fighter jet,” bossman intones, and although you groan as you recall the hell of your fluid dynamics courses, you realize that it should be easy enough to whip up a program to do the job. But then you remember that it’s like 1950, and that digital computers — at least ones that can fit in an airplane — haven’t been invented yet, and that you’re going to have to do this the hard way.
The scenario is obviously contrived, but this peek inside the Bendix MG-1 Central Air Data Computer reveals the engineer’s nightmare fuel that was needed to accomplish some pretty complex computations in a severely resource-constrained environment. As [Ken Shirriff] explains, this particular device was used aboard USAF fighter aircraft in the mid-50s, when the complexities of supersonic flight were beginning to outpace the instrumentation needed to safely fly in that regime. Thanks to the way air behaves near the speed of sound, a simple pitot tube system for measuring airspeed was no longer enough; analog computers like the MG-1 were designed to deal with these changes and integrate them into a host of other measurements critical to the pilot.
To be fair, [Ken] doesn’t do a teardown here, at least in the traditional sense. We completely understand that — this machine is literally stuffed full of a mind-boggling number of gears, cams, levers, differentials, shafts, and pneumatics. Taking it apart with the intention of getting it back together again would be a nightmare. But we do get some really beautiful shots of the innards, which reveal a lot about how it worked. Of particular interest are the torque-amplifying servo mechanism used in the pressure transducers, and the warped-plate cams used to finely adjust some of the functions the machine computes.
CAMBRDIGE, United Kingdom — “Quantum light” may sound like something out of a Marvel movie, but scientists say it may hold the real-world key to revolutionizing science as we know it. An international team says generating this high-energy light and controlling it can unlock a whole new realm in quantum computing.
Researchers from the University of Cambridge, as well as scientists in the United States, Israel, and Austria, have come up with a theory describing this new state of light. They say it has controllable quantum properties and a wide range of frequencies which reach X-ray levels. Harnessing this power could lead to advances in microscopy — or the ability to see incredibly small things normally invisible to the naked eye.
Life looks completely different at the atomic level.
Zhongli Pan is the recipient of the 2023 Distinguished Service Award by the Rice Technical Working Group, which will be presented at the 2023 RTWF Conference on February 20–23. The award recognizes individuals who have given distinguished long-term service to the rice industry in areas of research, education, international agriculture, administration and industry rice technology.
Post-harvest losses are common in the global food and agricultural industry. Research shows that storage grain pests can cause serious post-harvest losses, almost 9% in developed countries to 20% or more in developing countries. To address this problem, Zhongli Pan, an adjunct professor in the Department of Biological and Agricultural Engineering, has developed a potential solution.
Pan’s recent project using an IoT (Internet of Things) based smart wireless technology to remotely detect early insect activity in storage, processing, handling and transportation may solve the insect infestation related challenges for the agricultural industry. The technology uses a novel device called SmartProbe – designed by Pan and his team using wireless sensors and cameras – and leverages cloud computing to monitor and predict insect occurrences. This could help control insect pest, reduce food loss and the fumigants used in agricultural products today. Ragab Gebreil, a project scientist in Pan’s lab, is the co-inventor of this technology.
If life is common in our Universe, and we have every reason to suspect it is, why do we not see evidence of it everywhere? This is the essence of the Fermi Paradox, a question that has plagued astronomers and cosmologists almost since the birth of modern astronomy.
It is also the reasoning behind the Hart-Tipler Conjecture, one of the many (many!) proposed resolutions, which asserts that if advanced life had emerged in our galaxy sometime in the past, we would see signs of their activity everywhere we looked. Possible indications include self-replicating probes, megastructures, and other Type III-like activity.
On the other hand, several proposed resolutions challenge the notion that advanced life would operate on such massive scales. Others suggest that advanced extraterrestrial civilizations would be engaged in activities and locales that would make them less noticeable.
Researchers at the University of Göttingen have created a new approach to generate colored X-ray images. Previously, the only way to determine the chemical composition and arrangement of components in a sample using X-ray fluorescence analysis was to focus X-rays on the entire sample and scan it, which was both time-consuming and costly. The new method allows for the creation of an image of a large area with just one exposure, eliminating the need for focusing and scanning. The findings were published in the journal Optica.
In contrast to visible light, there are no comparably powerful lenses for “invisible” radiation, such as X-ray, neutron, or gamma radiation. However, these types of radiation are essential, for example, in nuclear medicine and radiology, as well as in industrial testing and material analysis.
Uses for X-ray fluorescence include analyzing the composition of chemicals in paintings and cultural artifacts to determine authenticity, origin, or production technique, or the analysis of soil samples or plants in environmental protection. The quality and purity of semiconductor components and computer chips can also be checked using X-ray fluorescence analysis.
Physics gets strange at the atomic scale. Scientists are utilizing quantum analog simulators – laboratory experiments that involve cooling numerous atoms to low temperatures and examining them using precisely calibrated lasers and magnets – to uncover, harness, and control these unusual quantum effects.
Scientists hope that any new understanding gained from quantum simulators will provide blueprints for designing new exotic materials, smarter and more efficient electronics, and practical quantum computers. But in order to reap the insights from quantum simulators, scientists first have to trust them.
That is, they have to be sure that their quantum device has “high fidelity” and accurately reflects quantum behavior. For instance, if a system of atoms is easily influenced by external noise, researchers could assume a quantum effect where there is none. But there has been no reliable way to characterize the fidelity of quantum analog simulators, until now.
