MIT researchers find that extratropical storm tracks would change significantly with solar geoengineering efforts.
Category: engineering – Page 62
Two-photon polymerization is a potential method for nanofabrication to integrate nanomaterials based on femtosecond laser-based methods. Challenges in the field of 3D nanoprinting include slow layer-by-layer printing and limited material options as a result of laser-matter interactions.
In a new report now on Science Advances, Chenqi Yi and a team of scientists in Technology Sciences, Medicine, and Industrial Engineering at the Wuhan University China and the Purdue University U.S., showed a new 3D nanoprinting approach known as free-space nanoprinting by using an optical force brush.
This concept allowed them to develop precise and spatial writing paths beyond optical limits to form 4D functional structures. The method facilitated the rapid aggregation and solidification of radicals to facilitate polymerization with increased sensitivity to laser energy, to provide high accuracy, free-space painting much like Chinese brush painting on paper.
face_with_colon_three Year 2017
A paper recently published in the journal Nuclear Engineering and Technology demonstrated the feasibility of using graphene to control hydrogen isotopes, specifically tritium.
Study: Adsorption of Hydrogen Isotopes on Graphene. Image Credit: Rost9/Shutterstock.com
Background
Tritium, a fast-decaying radioelement of hydrogen with one proton and two neutrons, is produced by nuclear reactors and by the interaction between cosmic rays and atmospheric particles. Tritium beta can diffuse through several materials, has 12.35 years half-life, and decays into helium-3.
Researchers at the University of Hong Kong (HKU) have designed an innovative pixelated, soft, color-changing system called a Morphable Concavity Array (MoCA).
Pixelated, soft, color-changing systems are malleable structures that can change color by manipulating light. They have applications in a wide range of industries, from medical bandages that change color if there is an infection, to foldable screens on smartphones and tablets, as well as wearable technology where sensors are integrated into the clothing fabric.
The research was co-directed by Professor Anderson Ho Cheung Shum from the Department of Mechanical Engineering at HKU, and Professor Mingzhu Li from the Institute of Chemistry, Chinese Academy of Sciences, and led by Dr. Yi Pan from the Department of Mechanical Engineering at HKU.
Ben Dixon, a researcher in the Optical and Quantum Communications Technology Group, explains how the process works: “First, you need to generate pairs of specific entangled qubits (called Bell states) and transmit them in different directions across the network link to two separate quantum repeaters, which capture and store these qubits. One of the quantum repeaters then does a two-qubit measurement between the transmitted and stored qubit and an arbitrary qubit that we want to send across the link in order to interconnect the remote quantum systems. The measurement results are communicated to the quantum repeater at the other end of the link; the repeater uses these results to turn the stored Bell state qubit into the arbitrary qubit. Lastly, the repeater can send the arbitrary qubit into the quantum system, thereby linking the two remote quantum systems.”
To retain the entangled states, the quantum repeater needs a way to store them — in essence, a memory. In 2020, collaborators at Harvard University demonstrated holding a qubit in a single silicon atom (trapped between two empty spaces left behind by removing two carbon atoms) in diamond. This silicon “vacancy” center in diamond is an attractive quantum memory option. Like other individual electrons, the outermost (valence) electron on the silicon atom can point either up or down, similar to a bar magnet with north and south poles. The direction that the electron points is known as its spin, and the two possible spin states, spin up or spin down, are akin to the ones and zeros used by computers to represent, process, and store information. Moreover, silicon’s valence electron can be manipulated with visible light to transfer and store a photonic qubit in the electron spin state. The Harvard researchers did exactly this; they patterned an optical waveguide (a structure that guides light in a desired direction) surrounded by a nanophotonic optical cavity to have a photon strongly interact with the silicon atom and impart its quantum state onto that atom. Collaborators at MIT then showed this basic functionality could work with multiple waveguides; they patterned eight waveguides and successfully generated silicon vacancies inside them all.
Lincoln Laboratory has since been applying quantum engineering to create a quantum memory module equipped with additional capabilities to operate as a quantum repeater. This engineering effort includes on-site custom diamond growth (with the Quantum Information and Integrated Nanosystems Group); the development of a scalable silicon-nanophotonics interposer (a chip that merges photonic and electronic functionalities) to control the silicon-vacancy qubit; and integration and packaging of the components into a system that can be cooled to the cryogenic temperatures needed for long-term memory storage. The current system has two memory modules, each capable of holding eight optical qubits.
Researchers led by Giulia Galli at University of Chicago’s Pritzker School of Molecular Engineering report a computational study that predicts the conditions to create specific spin defects in silicon carbide. Their findings, published online in Nature Communications, represent an important step towards identifying fabrication parameters for spin defects useful for quantum technologies.
Electronic spin defects in semiconductors and insulators are rich platforms for quantum information, sensing, and communication applications. Defects are impurities and/or misplaced atoms in a solid and the electrons associated with these atomic defects carry a spin. This quantum mechanical property can be used to provide a controllable qubit, the basic unit of operation in quantum technologies.
Yet the synthesis of these spin defects, typically achieved experimentally by implantation and annealing processes, is not yet well understood, and importantly, cannot yet be fully optimized. In silicon carbide —an attractive host material for spin qubits due to its industrial availability—different experiments have so far yielded different recommendations and outcomes for creating the desired spin defects.
Researchers at the Indian Institute of Science (IISc) have developed a fully indigenous gallium nitride (GaN) power switch that can have potential applications in systems like power converters for electric vehicles and laptops, as well as in wireless communications. The entire process of building the switch—from material growth to device fabrication to packaging—was developed in-house at the Center for Nano Science and Engineering (CeNSE), IISc.
Due to their high performance and efficiency, GaN transistors are poised to replace traditional silicon-based transistors as the building blocks in many electronic devices, such as ultrafast chargers for electric vehicles, phones and laptops, as well as space and military applications such as radar.
“It is a very promising and disruptive technology,” says Digbijoy Nath, Associate Professor at CeNSE and corresponding author of the study published in Microelectronic Engineering. “But the material and devices are heavily import-restricted … We don’t have gallium nitride wafer production capability at commercial scale in India yet.” The know-how of manufacturing these devices is also a heavily-guarded secret with few studies published on the details of the processes involved, he adds.
Ibrahim Can/Interesting Engineering.
This summer, we reported that Sansone was awarded the first prize, and winnings of $75,000, at this year’s Regeneron International Science and Engineering Fair (ISEF), the world’s largest international high school STEM competition.
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A new Boston Dynamics office in Frankfurt, Germany will provide sales, services, and field engineering support for European customers.