Computers Math

Scientists on the hunt for an unconventional kind of superconductor have produced the most compelling evidence to date that they’ve found one. In a pair of papers, researchers at the University of Maryland’s (UMD) Quantum Materials Center (QMC) and colleagues have shown that uranium ditelluride (or UTe2 for short) displays many of the hallmarks of a topological superconductor — a material that may unlock new ways to build quantum computers and other futuristic devices.
“Nature can be wicked,” says Johnpierre Paglione, a professor of physics at UMD, the director of QMC and senior author on one of the papers. “There could be other reasons we’re seeing all this wacky stuff, but honestly, in my career, I’ve never seen anything like it.”
All superconductors carry electrical currents without any resistance. It’s kind of their thing. The wiring behind your walls can’t rival this feat, which is one of many reasons that large coils of superconducting wires and not normal copper wires have been used in MRI machines and other scientific equipment for decades.
But superconductors achieve their super-conductance in different ways. Since the early 2000s, scientists have been looking for a special kind of superconductor, one that relies on an intricate choreography of the subatomic particles that actually carry its current.
This choreography has a surprising director: a branch of mathematics called topology. Topology is a way of grouping together shapes that can be gently transformed into one another through pushing and pulling. For example, a ball of dough can be shaped into a loaf of bread or a pizza pie, but you can’t make it into a donut without poking a hole in it. The upshot is that, topologically speaking, a loaf and a pie are identical, while a donut is different. In a topological superconductor, electrons perform a dance around each other while circling something akin to the hole in the center of a donut.
Unfortunately, there’s no good way to slice a superconductor open and zoom in on these electronic dance moves. At the moment, the best way to tell whether or not electrons are boogieing on an abstract donut is to observe how a material behaves in experiments. Until now, no superconductor has been conclusively shown to be topological, but the new papers show that UTe2 looks, swims and quacks like the right kind of topological duck. More

Electronic circuits that compute and store information contain millions of tiny switches that control the flow of electric current. A deeper understanding of how these tiny switches work could help researchers push the frontiers of modern computing.
Now scientists have made the first snapshots of atoms moving inside one of those switches as it turns on and off. Among other things, they discovered a short-lived state within the switch that might someday be exploited for faster and more energy-efficient computing devices.
The research team from the Department of Energy’s SLAC National Accelerator Laboratory, Stanford University, Hewlett Packard Labs, Penn State University and Purdue University described their work in a paper published in Science today.
“This research is a breakthrough in ultrafast technology and science,” says SLAC scientist and collaborator Xijie Wang. “It marks the first time that researchers used ultrafast electron diffraction, which can detect tiny atomic movements in a material by scattering a powerful beam of electrons off a sample, to observe an electronic device as it operates.”
Capturing the cycle
For this experiment, the team custom-designed miniature electronic switches made of vanadium dioxide, a prototypical quantum material whose ability to change back and forth between insulating and electrically conducting states near room temperature could be harnessed as a switch for future computing. The material also has applications in brain-inspired computing because of its ability to create electronic pulses that mimic the neural impulses fired in the human brain. More

By combining oil drops with water containing a detergent-like substance, the scientists found they could produce artificial swimmers that are able to swim independently and even harvest energy to recharge.
The oil droplets use fluctuating temperature changes in their surrounding environment to store energy and to swim. When cooled, the droplets release thin ‘tail-like’ threads into the environment. The friction generated between the tails and surrounding fluid, pushes the droplet causing them to move. On heating, the droplets then retract their tails returning to their original state, and harness the heat from their environment to recharge.
The researchers show that the droplets recharge multiple times and are able to swim for periods of up to 12 minutes at a time.
Dr Stoyan Smoukov, Reader in Chemical Engineering at Queen Mary University of London and author of the study, said: “In biology, research shows that to create even the simplest artificial cells we need over 470 genes. However, through this international collaboration, we show that just by using a few simple and inexpensive components we can create a new type of active matter that can change shape and move just like a living thing.”
“We hope that this study will open up the opportunity for people to engage in cutting-edge science. As the only equipment needed is a simple optical microscope, people could create these microswimmers with the most basic laboratory set-ups, or even at home. With thousands of swimmers per drop of water, it’s a world in a drop situation. And when it costs 7p per teaspoon, there’s plenty for everyone.”
Other types of artificial swimmers exist however their movements are either driven by chemical reactions, which create bubbles that propel the swimmers through fluids, or by physical forces such as magnetic or electric fields. Instead, this new class of swimmers, which are around the size of a red blood cell, are able to spontaneously assemble and move without using external forces.
As the swimmers are not harmful to other living things, the scientists hope they could be used to study the basic interactions between living organisms such as bacteria and algae.
“In nature we often see large numbers of organisms such as bacteria, grouping together but our understanding of how these organisms interact with each other is incomplete. By mixing our simple artificial swimmers with groups of living organisms we could develop a clearer picture of how biological microswimmers communicate with each other. For example, do they only communicate due to the physical act of ‘bumping’ into each other, or are there other chemicals or signals released into the environment essential for their interaction.”
Video: https://www.youtube.com/watch?v=OKe54UucXD8
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Researchers at UC San Francisco have successfully developed a “speech neuroprosthesis” that has enabled a man with severe paralysis to communicate in sentences, translating signals from his brain to the vocal tract directly into words that appear as text on a screen.
The achievement, which was developed in collaboration with the first participant of a clinical research trial, builds on more than a decade of effort by UCSF neurosurgeon Edward Chang, MD, to develop a technology that allows people with paralysis to communicate even if they are unable to speak on their own. The study appears July 15 in the New England Journal of Medicine.
“To our knowledge, this is the first successful demonstration of direct decoding of full words from the brain activity of someone who is paralyzed and cannot speak,” said Chang, the Joan and Sanford Weill Chair of Neurological Surgery at UCSF, Jeanne Robertson Distinguished Professor, and senior author on the study. “It shows strong promise to restore communication by tapping into the brain’s natural speech machinery.”
Each year, thousands of people lose the ability to speak due to stroke, accident, or disease. With further development, the approach described in this study could one day enable these people to fully communicate.
Translating Brain Signals into Speech
Previously, work in the field of communication neuroprosthetics has focused on restoring communication through spelling-based approaches to type out letters one-by-one in text. Chang’s study differs from these efforts in a critical way: his team is translating signals intended to control muscles of the vocal system for speaking words, rather than signals to move the arm or hand to enable typing. Chang said this approach taps into the natural and fluid aspects of speech and promises more rapid and organic communication. More

A football is not a quantum particle. There are crucial differences between the things we know from everyday life and tiny quantum objects. Quantum phenomena are usually very fragile. To study them, one normally uses only a small number of particles, well shielded from the environment, at the lowest possible temperatures.
Through a collaboration between the University of Vienna, the Austrian Academy of Sciences and TU Wien, however, it has now been possible to measure a hot glass sphere consisting of about one billion atoms with unprecedented precision and to control it at the quantum level. Its movement was deliberately slowed down until it assumed the ground state of lowest possible energy. The measurement method almost reached the limit set by Heisenberg’s uncertainty principle — physics just does not allow for any more precision than that. This was made possible by applying special methods from control engineering to quantum systems. The results have now been published in the scientific journal Nature.
Perfect precision is impossible
The measurement influences the measured object — this is one of the most basic principles of quantum theory. “Werner Heisenberg came up with a famous thought experiment — the so-called Heisenberg microscope” explains physicist Lorenzo Magrini, the first author of the study from the University of Vienna. “If you want to measure the position of an object very precisely under a microscope, you have to use light with the shortest possible wavelength. But short wavelength means higher energy, so the movement of the particle is disturbed more strongly.” You just cannot accurately measure the location and the state of motion of a particle at the same time. The product of their uncertainties is always limited by Planck’s constant — this is the so-called Heisenberg uncertainty principle. However, it is possible to find out how close one can get to this limit set by nature.
Prof. Markus Aspelmeyer’s team at the University of Vienna is investigating this using a glass sphere with a diameter of less than 200 nanometres, consisting of about one billion particles — very small by our everyday standards, but still very large compared to objects usually studied in quantum physics.
The glass sphere can be kept in place with a laser beam. The atoms of the sphere are heated up by the laser, and the internal temperature of the sphere rises to several hundred degrees Celsius. This means that the atoms of the glass sphere are wobbling around violently. In the experiment, however, it was not the wobbling movements of the individual atoms that were studied, but the collective motion of the sphere in the laser trap. “These are two completely different things, just as the movement of a pendulum in a pendulum clock is something different from the movement of the individual atoms inside the pendulum,” says Markus Aspelmeyer. More

More and more companies are using chatbots in customer services. Due to advances in artificial intelligence and natural language processing, chatbots are often indistinguishable from humans when it comes to communication. But should companies let their customers know that they are communicating with machines and not with humans? Researchers at the University of Göttingen investigated. Their research found that consumers tend to react negatively when they learn that the person they are talking to is, in fact, a chatbot. However, if the chatbot makes mistakes and cannot solve a customer’s problem, the disclosure triggers a positive reaction. The results of the study were published in the Journal of Service Management.
Previous studies have shown that consumers have a negative reaction when they learn that they are communicating with chatbots — it seems that consumers are inherently averse to the technology. In two experimental studies, the Göttingen University team investigated whether this is always the case. Each study had 200 participants, each of whom was put into the scenario where they had to contact their energy provider via online chat to update their address on their electricity contract following a move. In the chat, they encountered a chatbot — but only half of them were informed that they were chatting online with a non-human contact. The first study investigated the impact of making this disclosure depending on how important the customer perceives the resolution of their service query to be. In a second study, the team investigated the impact of making this disclosure depending on whether the chatbot was able to resolve the customer’s query or not. To investigate the effects, the team used statistical analyses such as covariance and mediation analysis.
The result: most noticeably, if service issues are perceived as particularly important or critical, there is a negative reaction when it is revealed that the conversation partner is a chatbot. This scenario weakens customer trust. Interestingly, however, the results also show that disclosing that the contact was a chatbot leads to positive customer reactions in cases where the chatbot cannot resolve the customer’s issue. “If their issue isn’t resolved, disclosing that they were talking with a chatbot, makes it easier for the consumer to understand the root cause of the error,” says first author Nika Mozafari from the University of Göttingen. “A chatbot is more likely to be forgiven for making a mistake than a human.” In this scenario, customer loyalty can even improve.
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The concept of interoperability describes the ability of different systems to communicate. This is a major challenge in biomedical research, and in particular, in the field of personalised medicine, which is largely based on the compilation and analysis of numerous datasets. For instance, the COVID-19 pandemic has shown that even when the technical, legal and ethical constraints are lifted, the data remain difficult to analyse because of semantic ambiguities. Under the auspices of the Swiss Personalized Health Network (SPHN) and in close collaboration with representatives from all five Swiss university hospitals and eHealth Suisse, a team of scientists from the University of Geneva (UNIGE) and the University Hospitals of Geneva (HUG), in collaboration with the SIB Swiss Institute of Bioinformatics and the Lausanne University Hospital (CHUV), have developed the strategy for a national infrastructure adopted by all Swiss university hospitals and academic institutions. With its pragmatic approach, this strategy is based on the development of a common semantic framework that does not aim to replace existing standards, but to use them in a synergistic and flexible way according to the needs of the research and the partners involved. The implementation of this strategy, which has already started, marks a crucial step to stimulate research and innovation for a truly personalised medicine in Switzerland. Read more in the journal JMIR Medical Informatics.
Personalised medicine is based on the exploitation and analysis of large quantities of data whether genomic, epidemiological or from medical imaging, to extract meaning. To be able to do this, cross-referencing and aggregating mutually intelligible data is compulsory, even when they come from very different sources.
With this in mind, the Swiss government created in 2017 the Swiss Personalized Health Network (SPHN), an initiative placed under the leadership of the Swiss Academy of Medical Sciences in collaboration with the SIB Swiss Institute of Bioinformatics that aims to promote the use and exchange of health data for research. “Despite major investments over the past decade, there are still major disparities,” says Christian Lovis, director of the Department of Radiology and Medical Informatics at the UNIGE Faculty of Medicine and head of the Division of Medical Information Sciences at the HUG. “This is why we wanted, with our partners and the SPHN, to propose a strategy and common standards that are flexible enough to accommodate all kinds of current and future databases.”
A three-pillar strategy
We communicate on three main standards: the meaning we give to things, because we must agree on a common basis for understanding each other; a technical standard — the sound, with which we speak; and finally, the organisation of the meaning and sound with sentences and grammar to structure the communication in an intelligible way. “In terms of data, it’s the same thing, explains Christophe Gaudet-Blavignac, a researcher in the team led by Christian Lovis. You have to agree on a semantic, to represent conceptually what has to be communicated. Then we need a compositional language to combine these meanings with all the freedom required to express everything that needs to be expressed. And finally, depending on the projects and research communities involved, this will be ‘translated’ as needed into data models, which are as numerous as the languages spoken in the world.”
“Our aim has therefore been to unify vocabularies so that they can be communicated in any grammar, rather than creating a new vocabulary from scratch that everybody would have to learn anew,” says Christian Lovis. “In this sense, the Swiss federalism is a huge advantage: it has forced us to imagine a decentralised strategy, which can be applied everywhere. The constraint has therefore created the opportunity to develop a system that works despite local languages, cultures and regulations.” This makes it possible to apply specific data models for only the last step to be adapted to the formats required by a particular project — the Food and Drug Administration (FDA) format in the case of collaboration with an American team, for example, or any other specific format used by a particular country or research initiative. This constitutes a guarantee of mutual understanding and a huge time saving.
No impact on data protection
However, data interoperability does not mean systematic data sharing. “The banking world, for example, has long since adopted global interoperability standards, stresses Christophe Gaudet-Blavignac. A simple IBAN can be used to transfer money from any account to any other. However, this does not mean that anyone, be they individuals, private organisations or governments, can know what is in these accounts without a strict legal framework.” Indeed, a distinction must be made between the instruments that create interoperability and their implementation, on the one hand, and the regulatory framework that governs their accessibility, on the other hand.
Strategy implementation
This strategy has been implemented stepwise in Switzerland since the middle of 2019, in the framework of the Swiss Personalized Health Network. “Swiss university hospitals are already following the proposed strategy to share interoperable data for all multicentric research projects funded by the SPHN initiative,” reports Katrin Crameri, director of the Personalized Health Informatics Group at SIB in charge of the SPHN Data Coordination Centre. Further, some hospitals are starting to implement this strategy beyond the SPHN initiative.
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Researchers have found evidence for an anomalous phase of matter that was predicted to exist in the 1960s. Harnessing its properties could pave the way to new technologies able to share information without energy losses. These results are reported in the journal Science Advances.
While investigating a quantum material, the researchers from the University of Cambridge who led the study observed the presence of unexpectedly fast waves of energy rippling through the material when they exposed it to short and intense laser pulses. They were able to make these observations by using a microscopic speed camera that can track small and very fast movement on a scale that is challenging with many other techniques. This technique probes the material with two light pulses: the first one disturbs it and creates waves — or oscillations — propagating outward in concentric circles, in the same way as dropping a rock into a pond; the second light pulse takes a snapshot of these waves at various times. Put together, these images allowed them to look at how these waves behave, and to understand their ‘speed limit.’
“At room temperature, these waves move at a hundredth of the speed of light, much faster than we would expect in a normal material. But when we go to higher temperatures, it is as if the pond has frozen,” explained first author Hope Bretscher, who carried out this research at Cambridge’s Cavendish Laboratory. “We don’t see these waves moving away from the rock at all. We spent a long time searching for why such bizarre behaviour could occur.”
The only explanation that seemed to fit all the experimental observations was that the material hosts, at room temperature, an “excitonic insulator” phase of matter, which while theoretically predicted, had eluded detection for decades.
“In an excitonic insulator, the observed waves of energy are supported by charge neutral particles that can move at electron-like velocities. Importantly, these particles could transport information without being hindered by the dissipation mechanisms that, in most common materials, affect charged particles like electrons,” said Dr Akshay Rao from the Cavendish Laboratory, who led the research. “This property could provide a simpler route toward room-temperature, energy-saving computation than that of superconductivity.”
The Cambridge team then worked with theorists around the world to develop a model about how this excitonic insulating phase exists, and why these waves behave in this way.
“Theorists predicted the existence of this anomalous phase decades ago, but the experimental challenges to see evidence of this has meant that only now we are able to apply previously developed frameworks to provide a better picture of how it behaves in a real material,” commented Yuta Murakami, from the Tokyo Institute of Technology, who collaborated on the study.
“The dissipationless energy transfer challenges our current understanding of transport in quantum materials and opens theorists’ imaginations to new ways for their future manipulation,” said collaborator Denis Gole?, from the Jozef Stefan Institute and University of Ljubljana.
“This work puts us a step closer toward achieving some incredibly energy-efficient applications that can harness this property, including in computers.” concluded Dr Rao.
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