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Computers & Math

Unconventional Heat Conductivity Toggled by Magnetic Fields in Semimetals

The ability to conduct heat is one of the most fundamental properties of matter, crucial for engineering applications. Scientists know well how conventional materials, such as metals and insulators, conduct heat. However, things are not as straightforward under extreme conditions such as temperatures close to absolute zero combined with strong magnetic fields, where strange quantum effects begin to dominate. This is particularly true in the realm of quantum materials.

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The discovery of unconventional heat conductivity in semimetals has sparked significant interest among scientists. Researchers from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), University of Bonn, and Centre national de la recherche scientifique (CNRS) have successfully demonstrated that magnetic fields can toggle heat conductivity in these materials. In a recent study published in PNAS, they exposed semimetal zirconium pentatelluride (ZrTe5) to high magnetic fields and very low temperatures, revealing dramatically enhanced heat oscillations caused by a novel mechanism.

Semimetals, such as ZrTe5, belong to the class of topological materials. These unique electronic structures make them extremely robust, leading to unconventional and often bizarre phenomena that could play a crucial role in advancing future quantum technologies. Notably, research and industry are currently investing considerable effort into developing quantum computers, with topological materials emerging as a promising avenue for their realization.

In metals like silver or copper, heat conduction is expected to oscillate when placed in strong magnetic fields at temperatures close to absolute zero. However, in semimetals, there are very few electrons available to transport heat, and as such, heat conduction is widely believed to be dominated by phonons – emergent particles that represent crystal lattice vibrations.

The researchers discovered a counterintuitive mechanism for the transport of heat under strong magnetic fields in semimetals. They found that thermal transport was indeed dominated by lattice vibrations but that the presence of strong magnetic fields dramatically enhanced the interaction between electrons and phonons, leading to quantum oscillations in conduction themselves.

“We have corroborated the existence of this unconventional phenomenon through the study of thermal conductivity and ultrasonic attenuation in semimetallic ZrTe₅ in strong magnetic fields and temperatures only a fraction of a degree above absolute zero,” Dr. Stanisław Gałeski explained. “In our experiment, we have detected clear thermal quantum oscillations with a frequency characteristic of the electronic sub-system.”

This principle is not limited to ZrTe5 but applies to all semimetals with low charge-carrier density – regardless of whether they are topological or not. The study suggests that the thermal conductivity of lattice vibrations can serve as a sensitive tool to study subtle quantum effects that might be barely detectable through other means.

The discovery has significant implications for advancing our understanding of heat transport in materials and could potentially lead to breakthroughs in quantum technology and magnetic-field sensor technologies. As scientists continue to explore this phenomenon, they may uncover new ways to harness the power of semimetals and unlock their full potential.

Computational Biology

A Quantum Leap Forward – New Amplifier Boosts Efficiency of Quantum Computers 10x

Chalmers engineers built a pulse-driven qubit amplifier that’s ten times more efficient, stays cool, and safeguards quantum states—key for bigger, better quantum machines.

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Quantum computers have long been touted as revolutionary machines capable of solving complex problems that stymie conventional supercomputers. However, their full potential has been hindered by the limitations of qubit amplifiers – essential components required to read and interpret quantum information. Researchers at Chalmers University of Technology in Sweden have taken a significant step forward with the development of an ultra-efficient amplifier that reduces power consumption by 90%, paving the way for more powerful quantum computers with enhanced performance.

The new amplifier is pulse-operated, meaning it’s activated only when needed to amplify qubit signals, minimizing heat generation and decoherence. This innovation has far-reaching implications for scaling up quantum computers, as larger systems require more amplifiers, leading to increased power consumption and decreased accuracy. The Chalmers team’s breakthrough offers a solution to this challenge, enabling the development of more accurate readout systems for future generations of quantum computers.

One of the key challenges in developing pulse-operated amplifiers is ensuring they respond quickly enough to keep pace with qubit readout. To address this, the researchers employed genetic programming to develop a smart control system that enables rapid response times – just 35 nanoseconds. This achievement has significant implications for the future of quantum computing, as it paves the way for more accurate and powerful calculations.

The new amplifier was developed in collaboration with industry partners Low Noise Factory AB and utilizes the expertise of researchers at Chalmers’ Terahertz and Millimeter Wave Technology Laboratory. The study, published in IEEE Transactions on Microwave Theory and Techniques, demonstrates a novel approach to developing ultra-efficient amplifiers for qubit readout and offers promising prospects for future research.

In conclusion, the development of this highly efficient amplifier represents a significant leap forward for quantum computing. By reducing power consumption by 90%, researchers have opened doors to more powerful and accurate calculations, unlocking new possibilities in fields such as drug development, encryption, AI, and logistics. As the field continues to evolve, it will be exciting to see how this innovation shapes the future of quantum computing.

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Artificial Intelligence

AI Uncovers Hidden Heart Risks in CT Scans: A Game-Changer for Cardiovascular Care

What if your old chest scans—taken years ago for something unrelated—held a secret warning about your heart? A new AI tool called AI-CAC, developed by Mass General Brigham and the VA, can now comb through routine CT scans to detect hidden signs of heart disease before symptoms strike.

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The Massachusetts General Brigham researchers have developed an innovative artificial intelligence (AI) tool called AI-CAC to analyze previously collected CT scans and identify individuals with high coronary artery calcium (CAC) levels, indicating a greater risk for cardiovascular events. Their research, published in NEJM AI, demonstrated the high accuracy and predictive value of AI-CAC for future heart attacks and 10-year mortality.

Millions of chest CT scans are taken each year, often in healthy people, to screen for lung cancer or other conditions. However, this study reveals that these scans can also provide valuable information about cardiovascular risk, which has been going unnoticed. The researchers found that AI-CAC had a high accuracy rate (89.4%) at determining whether a scan contained CAC or not.

The gold standard for quantifying CAC uses “gated” CT scans, synchronized to the heartbeat to reduce motion during the scan. However, most chest CT scans obtained for routine clinical purposes are “nongated.” The researchers developed AI-CAC, a deep learning algorithm, to probe through these nongated scans and quantify CAC.

The AI-CAC model was 87.3% accurate at determining whether the score was higher or lower than 100, indicating a moderate cardiovascular risk. Importantly, AI-CAC was also predictive of 10-year all-cause mortality, with those having a CAC score over 400 having a 3.49 times higher risk of death over a 10-year period.

The researchers hope to conduct future studies in the general population and test whether the tool can assess the impact of lipid-lowering medications on CAC scores. This could lead to the implementation of AI-CAC in clinical practice, enabling physicians to engage with patients earlier, before their heart disease advances to a cardiac event.

As Dr. Raffi Hagopian, first author and cardiologist at the VA Long Beach Healthcare System, emphasized, “Using AI for tasks like CAC detection can help shift medicine from a reactive approach to the proactive prevention of disease, reducing long-term morbidity, mortality, and healthcare costs.”

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Communications

Artificial Intelligence Isn’t Hurting Workers—It Might Be Helping

Despite widespread fears, early research suggests AI might actually be improving some aspects of work life. A major new study examining 20 years of worker data in Germany found no signs that AI exposure is hurting job satisfaction or mental health. In fact, there s evidence that it may be subtly improving physical health especially for workers without college degrees by reducing physically demanding tasks. However, researchers caution that it s still early days.

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The relationship between artificial intelligence (AI) and worker well-being has been a topic of concern. However, a recent study suggests that AI exposure may not be causing widespread harm to mental health or job satisfaction. In fact, the data indicates that AI might even be linked to modest improvements in physical health, particularly among employees with less than a college degree.

The study, “Artificial Intelligence and the Wellbeing of Workers,” published in Nature: Scientific Reports, analyzed two decades of longitudinal data from the German Socio-Economic Panel. The researchers explored how workers in AI-exposed occupations fared compared to those in less-exposed roles.

“We find little evidence that AI adoption has undermined workers’ well-being on average,” said Professor Luca Stella, one of the study’s authors. “If anything, physical health seems to have slightly improved, likely due to declining job physical intensity and overall job risk in some of the AI-exposed occupations.”

However, the researchers also highlight reasons for caution. The analysis relies primarily on a task-based measure of AI exposure, which may not capture the full effects of AI adoption. Alternative estimates based on self-reported exposure reveal small negative effects on job and life satisfaction.

“We may simply be too early in the AI adoption curve to observe its full effects,” Stella emphasized. “AI’s impact could evolve dramatically as technologies advance, penetrate more sectors, and alter work at a deeper level.”

The study’s key findings include:

1. Modest improvements in physical health among employees with less than a college degree.
2. Little evidence of widespread harm to mental health or job satisfaction.
3. Small negative effects on job and life satisfaction reported by workers with self-reported exposure to AI.

The researchers note that the sample excludes younger workers and only covers the early phases of AI diffusion in Germany. They caution that outcomes may differ in more flexible labor markets or among younger cohorts entering increasingly AI-saturated workplaces.

“This research is an early snapshot, not the final word,” said Professor Osea Giuntella, another author of the study. “As AI adoption accelerates, continued monitoring of its broader impacts on work and health is essential.”

Ultimately, the study suggests that the impact of AI on worker well-being may be more complex than initially thought. While it is too soon to draw definitive conclusions, the research highlights the need for ongoing monitoring and analysis of AI’s effects on the workforce.

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