Computers Math

Research led by the University of Kent and the STFC Rutherford Appleton Laboratory has resulted in the discovery of a new rare topological superconductor, LaPt3P. This discovery may be of huge importance to the future operations of quantum computers.
Superconductors are vital materials able to conduct electricity without any resistance when cooled below a certain temperature, making them highly desirable in a society needing to reduce its energy consumption.
Superconductors manifest quantum properties on the scale of everyday objects, making them highly attractive candidates for building computers which use quantum physics to store data and perform computing operations, and can vastly outperform even the best supercomputers in certain tasks. As a result, there is an increasing demand from leading tech companies like Google, IBM and Microsoft to make quantum computers on an industrial scale using superconductors.
However, the elementary units of quantum computers (qubits) are extremely sensitive and lose their quantum properties due to electromagnetic fields, heat and collisions with air molecules. Protection from these can be achieved by making more resilient qubits using a special class of superconductors called topological superconductors which in addition to being superconductors also host protected metallic states on their boundaries or surfaces.
Topological superconductors, such as LaPt3P, newly discovered through muon spin relaxation experiments and extensive theoretical analysis, are exceptionally rare and are of tremendous value to the future industry of quantum computing.
To ensure its properties are sample and instrument independent, two different sets of samples were prepared in the University of Warwick and in ETH Zurich. Muon experiments were then performed in two different types of muon facilities: in the ISIS Pulsed Neutron and Muon Source in the STFC Rutherford Appleton Laboratory and in PSI, Switzerland.
Dr Sudeep Kumar Ghosh, Leverhulme Early Career Fellow at Kent and Principle Investigator said: ‘This discovery of the topological superconductor LaPt3P has tremendous potential in the field of quantum computing. Discovery of such a rare and desired component demonstrates the importance of muon research for the everyday world around us.’
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Materials provided by University of Kent. Original written by Sam Wood. Note: Content may be edited for style and length. More

A new model that applies artificial intelligence to carbohydrates improves the understanding of the infection process and could help predict which viruses are likely to spread from animals to humans. This is reported in a recent study led by researchers at the University of Gothenburg.
Carbohydrates participate in nearly all biological processes — yet they are still not well understood. Referred to as glycans, these carbohydrates are crucial to making our body work the way it is supposed to. However, with a frightening frequency, they are also involved when our body does not work as intended. Nearly all viruses use glycans as their first contact with our cells in the process of infection, including our current menace SARS-CoV-2, causing the COVID-19 pandemic.
A research group led by Daniel Bojar, assistant professor at the University of Gothenburg, has now developed an artificial intelligence-based model to analyze glycans with an unprecedented level of accuracy. The model improves the understanding of the infection process by making it possible to predict new virus-glycan interactions, for example between glycans and influenza viruses or rotaviruses: a common cause for viral infections in infants.
As a result, the model can also lead to a better understanding of zoonotic diseases, where viruses spread from animals to humans.
“With the emergence of SARS-CoV-2, we have seen the potentially devastating consequences of viruses jumping from animals to humans. Our model can now be used to predict which viruses are particularly close to “jumping over.” We can analyze this by seeing how many mutations would be necessary for the viruses to recognize human glycans, which increases the risk of human infection. Also, the model helps us predict which parts of the human body are likely targeted by a potentially zoonotic virus, such as the respiratory system or the gastrointestinal tract,” says Daniel Bojar, who is the main author of the study.
In addition, the research group hopes to leverage the improved understanding of the infection process to prevent viral infection. The aim is to use the model to develop glycan-based antivirals, medicines that suppress the ability of viruses to replicate.
“Predicting virus-glycan interactions means we can now search for glycans that bind viruses better than our own glycans do, and use these “decoy” glycans as antivirals to prevent viral infection. However, further advances in glycan manufacturing are necessary, as potential antiviral glycans might include diverse sequences that are currently difficult to produce,” Daniel Bojar says.
He hopes the model will constitute a step towards including glycans in approaches to prevent and combat future pandemics, as they are currently neglected in favor of molecules that are simpler to analyze, such as DNA.
“The work of many groups in recent years has really revolutionized glycobiology and I think we are finally at the cusp of using these complex biomolecules for medical purposes. Exciting times are ahead,” says Daniel Bojar.
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Materials provided by University of Gothenburg. Original written by Ulrika Ernström. Note: Content may be edited for style and length. More

Near-field light is invisible light at the subwavelength scale. Harnessed for a variety of practical applications, such as wireless power transfer, near-field light has an increasingly significant role in the development of miniature on-chip photonic devices. Controlling the direction of near-field light propagation has been an ongoing challenge that is of fundamental interest in photonics physics and can significantly advance a variety of applications.
So far, propagation of near-field light in a single direction is achieved by specific interactions between the electric dipole and the magnetic dipole in a system, which has led to inevitable complexities in device design. Hyperbolic metamaterials (HMMs), an important class of artificial anisotropic material with hyperbolic isofrequency contours, have attracted attention due to their unique ability to control near-field light by enabling subwavelength confinement of electromagnetic waves. Large wave-vector modes in HMMs are of particular interest because those modes are easier to integrate and have a smaller loss of energy at transfer.
As reported in Advanced Photonics, researchers from Tongji University in China recently demonstrated an all-electric scheme able to flexibly control the propagation direction of near-field light. They reported anomalous unidirectional excitation of hyperbolic modes with large wave-vector at subwavelength scales. According to their research, selective near-field coupling in HMMs is enabled by discrete electric dipoles with different phases, which serve as a metasource composed of all-electric components and with a symmetry-associated inner freedom.
Their research not only addresses the need for an all-electric experimental design scheme for near-field photonics, but also contributes fundamentally valuable symmetry-based excitation principles. Using a Huygens metasource, the researchers were able to observe the unidirectional excitation of hyperbolic bulk modes in a planar HMM. They found that unidirectional excitation in free space is the same as in the vertical direction, but opposite to that in the horizontal direction. These different propagation characteristics in horizontal and vertical directions are unique to the hyperbolic modes. In addition, the researchers used spin metasources to study the directional propagation of light in a planar hyperbolic waveguide. They found that, for the clockwise-rotating spin metasource, only the guided mode propagating from right to left is excited. And for the counterclockwise-rotating source, only the guided mode propagating from left to right is excited.
Overall, the research advances the fields of optical science and information communication, as the results provide the necessary conditions for highly efficient and experimentally verified photonics routing. For emerging applications in integrated optical devices, as well as wireless power transfer, switching, and filtering, this work promises unprecedented flexible control of near-field light.
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Materials provided by SPIE–International Society for Optics and Photonics. Note: Content may be edited for style and length. More

Quantum technologies are based on quantum properties of light, electrons, and atoms. In recent decades, scientists have learned to master these phenomena and exploit them in applications. Thus, the construction of a quantum computer for commercial applications is also coming within reach. One of the emerging technologies that is currently being advanced very successfully is ion trap quantum computers. Here, charged particles are trapped with electromagnetic fields in a vacuum chamber and prepared in such a way that they can serve as carriers for information and be used for computing, which includes cooling them to the lowest temperatures permitted by quantum mechanics. However, the quantum mechanical properties exploited in this process are highly error prone. Even the smallest deficiencies can heat up the strongly cooled particles and thereby lead to errors in the processing of quantum information.
Possible sources of such faults are weakly conducting or non-conducting materials, which are used, for example, as insulators in a metallic ion trap, or optics, which are necessary for coupling ions with laser light. “Even for ion traps made exclusively of metal, oxide layers on the metals would cause such failures,” explains Tracy Northup at the Department of Experimental Physics of the University of Innsbruck in Austria. Northups team together with collaborators in Innsbruck and in the U.S. have found a way to determine the influence of dielectric materials on the charged particles in ion traps.
Experimentally confirmed
This was achieved because the Innsbruck quantum physicists have an ion trap in which they can precisely set the distance between the ions and dielectric optics. Based on an earlier proposal by Rainer Blatt’s group, the physicists computed the amount of noise caused by the dielectric material for this ion trap and compared it with data from experiment. “Theory and experiment agree very well, confirming that this method is well suited for determining the influence of dielectric materials on the ions,” explains Markus Teller from the Innsbruck team. To calculate the noise, the so-called fluctuation-dissipation theorem from statistical physics was used, which mathematically describes the response of a system in thermal equilibrium to a small external perturbation.
“In quantum computers, there are many possible sources of noise, and it is very difficult to sort out the exact sources,” says Tracy Northup. “Our method is the first to quantify the influence of dielectric materials in a given ion trap on the charged particles. In the future, designers of ion trap quantum computers will be able to assess this effect much more accurately and design their devices to minimize these perturbations.” After having successfully demonstrated the method on their own ion trap, the Innsbruck physicists now want to apply it to the ion traps of collaborators in the U.S. and Switzerland.
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The future of quantum computing may depend on the further development and understanding of semiconductor materials known as transition metal dichalcogenides (TMDCs). These atomically thin materials develop unique and useful electrical, mechanical, and optical properties when they are manipulated by pressure, light, or temperature.
In research published today in Nature Communications, engineers from Rensselaer Polytechnic Institute demonstrated how, when the TMDC materials they make are stacked in a particular geometry, the interaction that occurs between particles gives researchers more control over the devices’ properties. Specifically, the interaction between electrons becomes so strong that they form a new structure known as a correlated insulating state. This is an important step, researchers said, toward developing quantum emitters needed for future quantum simulation and computing.
“There is something exciting going on,” said Sufei Shi, an assistant professor of chemical and biological engineering at Rensselaer, who led this work. “One of the quantum degrees of freedom that we hope to use in quantum computing is enhanced when this correlated state exists.”
Much of Shi’s research has focused on gaining a better understanding of the potential of the exciton, which is formed when an electron, excited by light, bonds with a hole — a positively charged version of the electron. Shi and his team have demonstrated this phenomenon in TMDC devices made of layers of Tungsten disulfide (WS2) and Tungsten diselenide (WSe2). Recently, the team also observed the creation of an interlayer exciton, which is formed when an electron and hole exist in two different layers of material. The benefit of this type of exciton, Shi said, is that it holds a longer lifetime and responds more significantly to an electric field — giving researchers greater ability to manipulate its properties.
In their latest research, Shi and his team showed how, by stacking TMDCs in a particular manner, they can develop a lattice known as a moiré superlattice. Picture two sheets of paper stacked on top of one another, each with the same pattern of hexagons cut out of them. If you were to shift the angle of one of the pieces of paper, the hexagons would no longer perfectly match up. The new formation is similar to that of a moiré superlattice.
The benefit of such a geometry, Shi said, is that it encourages electrons and interlayer excitons to bond together, further increasing the amount of control researchers have over the excitons themselves. This discovery, Shi said, is an important step toward developing quantum emitters that will be needed for future quantum simulation and quantum computing.
“It has essentially opened the door to a new world. We see a lot of things already, just by peeking through the door, but we have no idea what is going to happen if we open the door and get inside,” Shi said. “That is what we want to do, we want to open the door and get inside.”
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Scientific studies describing the most basic processes often have the greatest impact in the long run. A new work by Rice University engineers could be one such, and it’s a gas, gas, gas for nanomaterials.
Rice materials theorist Boris Yakobson, graduate student Jincheng Lei and alumnus Yu Xie of Rice’s Brown School of Engineering have unveiled how a popular 2D material, molybdenum disulfide (MoS2), flashes into existence during chemical vapor deposition (CVD).
Knowing how the process works will give scientists and engineers a way to optimize the bulk manufacture of MoS2 and other valuable materials classed as transition metal dichalcogenides (TMDs), semiconducting crystals that are good bets to find a home in next-generation electronics.
Their study in the American Chemical Society journal ACS Nano focuses on MoS2’s “pre-history,” specifically what happens in a CVD furnace once all the solid ingredients are in place. CVD, often associated with graphene and carbon nanotubes, has been exploited to make a variety of 2D materials by providing solid precursors and catalysts that sublimate into gas and react. The chemistry dictates which molecules fall out of the gas and settle on a substrate, like copper or silicone, and assemble into a 2D crystal.
The problem has been that once the furnace cranks up, it’s impossible to see or measure the complicated chain of reactions in the chemical stew in real time.
“Hundreds of labs are cooking these TMDs, quite oblivious to the intricate transformations occurring in the dark oven,” said Yakobson, the Karl F. Hasselmann Professor of Materials Science and NanoEngineering and a professor of chemistry. “Here, we’re using quantum-chemical simulations and analysis to reveal what’s there, in the dark, that leads to synthesis.”
Yakobson’s theories often lead experimentalists to make his predictions come true. (For example, boron buckyballs.) This time, the Rice lab determined the path molybdenum oxide (MoO3) and sulfur powder take to deposit an atomically thin lattice onto a surface. More

A new high-performance plastic foam developed from whey proteins can withstand extreme heat better than many common thermoplastics made from petroleum. A research team in Sweden reports that the material, which may be used for example in catalysts for cars, fuel filters or packaging foam, actually improves its mechanical performance after days of exposure to high temperatures.
Reporting in Advanced Sustainable Systems, researchers from KTH Royal Institute of Technology in Stockholm say the research opens the door to using protein-based foam materials in potentially tough environments, such as filtration, thermal insulation and fluid absorption.
The basic building blocks of the material are protein nanofibrils, or PNFs, which are self-assembled from hydrolyzed whey proteins — a product from cheese-processing — under specific temperature and pH conditions.
In tests the foams improved with aging. After one month of exposure to a temperature of 150C, the material became stiffer, tougher and stronger, says the study’s co-author, Mikael Hedenqvist , professor in the Division of Polymeric Materials at KTH.
“This material only gets stronger with time,” he says. “If we compare with petroleum-based, commercial foam materials made of polyethylene and polystyrene, they melt instantly and decompose under the same harsh conditions.”
Proteins are often water-soluble, which poses a challenge when developing protein-based materials. Despite this, the material proved water-resistant after the aging process, which polymerized the protein, creating new covalent bonds that stabilized the foams. The foam also resisted even more aggressive substances — such as surfactants and reducing agents — that normally decompose or dissolve proteins. The crosslinking also made the foam unaffected by diesel fuel or hot oil.
The material also showed better fire resistance than commonly used polyurethane thermoset.
“This biodegradable, sustainable material can be a viable option for use in aggressive environments where fire resistance is important,” Hedenqvist says.
Potential applications include providing support for catalytic metals that operate at higher temperatures, such as platinum catalysts for automobiles. The material could conceivably work as a fuel filter, too.
Other possibilities are to use it as packaging foam and in applications for sound and thermal insulation where higher temperatures may occur and where there is a risk of an aggressive environment.
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Materials provided by KTH, Royal Institute of Technology. Note: Content may be edited for style and length. More

Advancements in wearable technology are reshaping the way we live, work and play, and also how healthcare is delivered and received. Wearables that have weaved their way into everyday life include smart watches and wireless earphones, while in the healthcare setting, common devices include wearable injectors, electrocardiogram (ECG) monitoring patches, listening aids, and more.
A major pain point facing the use of these wearables is the issue of keeping these devices properly and conveniently powered. As the number of wearables one uses increases, the need to charge multiple batteries rises in tandem, consuming huge amounts of electricity. Many users find it cumbersome to charge numerous devices every day, and inconvenient service disruptions occur when batteries run out.
A research team, led by Associate Professor Jerald Yoo from the Department of Electrical and Computer Engineering and the N.1 Institute for Health at the National University of Singapore (NUS), has developed a solution to these problems. Their technology enables a single device, such as a mobile phone placed in the pocket, to wirelessly power other wearable devices on a user’s body, using the human body as a medium for power transmission. The team’s novel system has an added advantage — it can harvest unused energy from electronics in a typical home or office environment to power the wearables.
Their achievement was first published in the journal Nature Electronics on 10 June 2021. It is the first of its kind to be established among existing literature on electronic wearables.
Using the human body as a medium for energy transmission
To extend battery life and sustain fully autonomous — yet wireless — operations of wearable devices, power transmission and energy harvesting approaches are required. However, conventional approaches for powering up body area wearables are limited by the distance that power can be transmitted, the “path” the energy can travel without facing obstacles, and the stability of energy movement. As such, none of the current methods have been able to provide sustainable power to wearables placed around the entire human body.
The NUS team decided to turn the tables on these limitations by designing a receiver and transmitter system that uses the very obstacle in wireless powering — the human body — as a medium for power transmission and energy harvesting. Each receiver and transmitter contains a chip that is used as a springboard to extend coverage over the entire body.
A user just needs to place the transmitter on a single power source, such as the smart watch on a user’s wrist, while multiple receivers can be placed anywhere on the person’s body. The system then harnesses energy from the source to power multiple wearables on the user’s body via a process termed as body-coupled power transmission. In this way, the user will only need to charge one device, and the rest of the gadgets that are worn can simultaneously be powered up from that single source. The team’s experiments showed that their system allows a single power source that is fully charged to power up to 10 wearable devices on the body, for a duration of over 10 hours.
As a complementary source of power, the NUS team also looked into harvesting energy from the environment. Their research found that typical office and home environments have parasitic electromagnetic (EM) waves that people are exposed to all the time, for instance, from a running laptop. The team’s novel receiver scavenges the EM waves from the ambient environment, and through a process referred to as body-coupled powering, the human body is able to harvest this energy to power the wearable devices, regardless of their locations around the body.
Paving the way for smaller, battery-less wearables
On the benefits of his team’s method, Assoc Prof Yoo said, “Batteries are among the most expensive components in wearable devices, and they add bulk to the design. Our unique system has the potential to omit the need for batteries, thereby enabling manufacturers to miniaturise the gadgets while reducing production cost significantly. More excitingly, without the constraints of batteries, our development can enable the next generation wearable applications, such as ECG patches, gaming accessories, and remote diagnostics.”
The NUS team will continue to enhance the powering efficiency of their transmitter/receiver system, with hopes that in future, any given power-transmitting device, be it a user’s mobile phone or smart watch, can satisfy the network power demands of all other wearables on the body, thus enabling a longer battery lifetime. More