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Archive for the ‘computing’ category

Feb 14, 2020

Quantum anomalous Hall effect in intrinsic magnetic topological insulator

Posted by in categories: computing, quantum physics

Nontrivial band topology can combine with magnetic order in a magnetic topological insulator to produce exotic states of matter such as quantum anomalous Hall (QAH) insulators and axion insulators. An aim of condensed matter physics is to find new materials with useful properties and apply quantum mechanics to study them. The field has allowed physicists to better understand the uses of magnets for hard disk data storage, computer displays and other technologies. The recent discovery of topological insulators have attracted broad interest and researchers predict that the interplay between ferromagnetism and the topological insulator state can realize a range of exotic quantum magnetic phenomena of interest in fundamental physics and device applications.

In a new report, Yujun Deng and a research team at the departments of physics and quantum matter physics in China, probed quantum transport in a thin flake MnBi2Te4 topological insulator, with intrinsic magnetic order. The ferromagnetic layers coupled anti-parallelly to each other in the atomically thin MnBi2Te4 layered van der Waals crystal. However, the sample became ferromagnetic when it contained an odd number of septuple layers. The research team observed the zero-field QAH effect in a five-septuple-layer specimen at 1.4 Kelvin. The results established MnBi2Te4 as an ideal platform to explore exotic topological phenomena with spontaneously broken time-reversal symmetry. The work is now published on Science.

Topological materials distinctly contain topologically protected quantum states that are robust against local distresses. For instance, in a topological insulator (TI) such as bismuth telluride (Bi2Te3), the bulk band topology can guarantee the existence of two-dimensional (2-D) surface states with gapless Dirac dispersion. By introducing magnetism into the initially time-reversal invariant topological insulators (TIs), scientists can induce profound changes in their electronic structure. For example, to experimentally observe the QAH effect in chromium-doped (Bi, Sb)2Te3, physicists had to precisely control the ratio of multiple elements in a non-stoichiometric material. Fine-tuning the material required reconciling conflicting demands and therefore, researchers had to precisely quantize the anomalous Hall effect only at temperatures up to T = 2 K, far below the Curie temperature and exchange gap in the material.

Feb 13, 2020

New material has highest electron mobility among known layered magnetic materials

Posted by in categories: computing, particle physics

All the elements are there to begin with, so to speak; it’s just a matter of figuring out what they are capable of—alone or together. For Leslie Schoop’s lab, one recent such investigation has uncovered a layered compound with a trio of properties not previously known to exist in one material.

With an international interdisciplinary team, Schoop, assistant professor of chemistry, and Postdoctoral Research Associate Shiming Lei, published a paper last week in Science Advances reporting that the van der Waals material gadolinium tritelluride (GdTe3) displays the highest electronic mobility among all known layered . In addition, it has magnetic order, and can easily be exfoliated.

Combined, these properties make it a promising candidate for new areas like magnetic twistronic devices and spintronics, as well as advances in data storage and device design.

Feb 12, 2020

Tabletop storage: Georgia Tech looks to SMASH an exabyte into DNA ‘sugar cube’

Posted by in categories: biotech/medical, computing, genetics

Georgia Tech Research Institute (GTRI) is looking into ways to speed up DNA-based cold storage in a $25m Scalable Molecular Archival Software and Hardware (SMASH) project.

DNA is a biopolymer molecule composed from two chains in a double helix formation, and carrying genetic information. The chains are made up from nucleotides containing one of four nucleobases; cytosine ©, guanine (G), adenine (A) and thymine (T). Both chains carry the same data, which is encoded into sequences of the four nucleobases.

GTRI senior research scientist Nicholas Guise said in a quote that DNA storage is “so compact that a practical DNA archive could store an exabyte of data, equivalent to a million terabyte hard drives, in a volume about the size of a sugar cube.”

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Feb 12, 2020

Classical time crystals could exist in nature, say physicists

Posted by in categories: computing, physics

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Computer simulations show coupled oscillators behave as “activated time crystals”.

Feb 11, 2020

Mathematicians Are Studying Planet-Sized Quantum Computers With God-Like Powers

Posted by in categories: computing, mathematics, quantum physics

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New research has exploded the space of problems that quantum computers can efficiently verify, simultaneously knocking down milestone problems in quantum physics and math.

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Feb 11, 2020

Engineers Just Built an Impressively Stable Quantum Silicon Chip From Artificial Atoms

Posted by in categories: computing, particle physics, quantum physics

Newly created artificial atoms on a silicon chip could become the new basis for quantum computing.

Engineers in Australia have found a way to make these artificial atoms more stable, which in turn could produce more consistent quantum bits, or qubits — the basic units of information in a quantum system.

The research builds on previous work by the team, wherein they produced the very first qubits on a silicon chip, which could process information with over 99 percent accuracy. Now, they have found a way to minimise the error rate caused by imperfections in the silicon.

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Feb 10, 2020

DNA-like material could bring even smaller transistors

Posted by in categories: computing, nanotechnology

Computer chips use billions of tiny switches, called transistors, to process information. The more transistors on a chip, the faster the computer.

A material shaped like a one-dimensional DNA helix might further push the limits on a transistor’s size. The material comes from a rare earth element called tellurium.

Researchers found that the material, encapsulated in a nanotube made of boron nitride, helps build a with a diameter of two nanometers. Transistors on the market are made of bulkier silicon and range between 10 and 20 nanometers in scale.

Feb 10, 2020

The human brain’s meticulous interface with the bloodstream now on a precision chip

Posted by in categories: biotech/medical, computing, neuroscience

A scrupulous gatekeeper stands between the brain and its circulatory system to let in the good and keep out the bad, but this porter, called the blood-brain barrier, also blocks trial drugs to treat diseases like Alzheimer’s or cancer from getting into the brain.

Now a team led by researchers at the Georgia Institute of Technology has engineered a way of studying the barrier more closely with the intent of helping drug developers do the same. In a new study, the researchers cultured the human on a , recreating its physiology more realistically than predecessor chips.

The new chip devised a healthy environment for the barrier’s central component, a brain cell called the , which is not a neuron, but which acts as neurons’ intercessors with the circulatory system. Astrocytes interface in with cells in the vasculature called endothelial cells to collaborate with them as the blood-brain barrier.

Feb 9, 2020

Galaxy formation simulated without dark matter

Posted by in categories: computing, cosmology

For the first time, researchers from the Universities of Bonn and Strasbourg have simulated the formation of galaxies in a universe without dark matter. To replicate this process on the computer, they have instead modified Newton’s laws of gravity. The galaxies that were created in the computer calculations are similar to those we actually see today. According to the scientists, their assumptions could solve many mysteries of modern cosmology. The results are published in the Astrophysical Journal.

Cosmologists today assume that matter was not distributed entirely evenly after the Big Bang. The denser places attracted more matter from their surroundings due to their stronger gravitational forces. Over the course of several billion years, these accumulations of gas eventually formed the galaxies we see today.

An important ingredient of this theory is the so-called . On the one hand, it is said to be responsible for the initial uneven distribution that led to the agglomeration of the gas clouds. It also explains some puzzling observations. For instance, stars in rotating galaxies often move so fast that they should actually be ejected. It appears that there is an additional source of gravity in the galaxies that prevents this—a kind of “star putty” that cannot be seen with telescopes: dark matter.

Feb 9, 2020

Information theft via manipulating screen brightness in air-gapped computers

Posted by in categories: computing, internet, security, surveillance

Data can be stolen from an air gapped personal computer just by using variations in screen brightness. Researchers at Ben-Gurion University wrote a paper on it.

As the team defines them, “Air-gapped computers are systems that are kept isolated from the Internet since they store or process .”

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