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Category: particle physics

‘Aquila Booster’ challenges theoretical limits of particle acceleration in pulsar wind nebulae

The Large High Altitude Air Shower Observatory (LHAASO) has detected PeV (1015 eV) gamma-ray emission from a pulsar wind nebula powered by PSR J1849-0001 in the constellation Aquila, marking the discovery of a new PeVatron and posing a challenge to the classical theory of particle acceleration in pulsar wind nebulae.

This discovery is important because the calculated particle acceleration efficiency of this celestial structure approaches or even exceeds the theoretical limits allowed under ideal magnetohydrodynamic conditions.

This study, published in Nature Astronomy, was conducted by Prof. Liu Ruoyu, Dr. Wang Kai, and doctoral student Tong Chaonan from Nanjing University, Prof. Chen Songzhan and Assoc. Prof. Wang Lingyu from the Institute of High Energy Physics of the Chinese Academy of Sciences, and their collaborators.

Carbon nanotubes are closing the gap on copper conductivity

Carbon nanotubes are one technology that many observers believe hasn’t quite lived up to the extreme hype that surrounded them when they first appeared on the scene in the late 1990s. At that time, much was made of their extraordinary electrical, thermal, and mechanical properties, with predictions that they would revolutionize materials science, electronics, and daily life. But could we be closer to realizing some of that promise?

In a paper published in the journal Science, researchers describe a method for adding a chemical to carbon nanotube bundles that brings them closer to copper’s ability to conduct electricity.

Carbon nanotubes are nanoscale hollow cylinders of carbon atoms, a structure that allows electricity to flow through them with very low resistance. However, when you bundle millions of them together, as you would need for practical applications like power lines and electrical wiring, they lose some of their exceptional conductivity. Electrons move easily along individual nanotubes, but transferring charge between neighboring tubes in a bundle is much less efficient.

New approach to detect ultra-rare part-per-sextillion isotopes could also sharpen dark matter searches

The detection and study of isotopes, atoms of the same element that have different numbers of neutrons, could expand the scope of physics research and enable new scientific discoveries. So far, rare isotopes have been primarily detected using a technique known as accelerator mass spectrometry (AMS), which accelerates atoms, to then measure their mass and charge.

Despite its widespread use, AMS is not always precise at the ultra-rare level, as it is susceptible to what is known as background interference. This essentially means that similar atoms or neighboring isotopes can produce misleading signals that reduce the accuracy and precision of measurements.

Researchers at the University of Science and Technology of China and the Chinese Academy of Sciences recently developed a new technique for detecting and counting individual atoms called Atom Trap Trace Analysis (ATTA).

One-way phonon synchronization could survive noise and defects, theoretical physicists suggest

A novel approach for realizing the one-way quantum synchronization of phonons has been proposed by three theoretical physicists at RIKEN. Importantly, this method is remarkably resilient against practical challenges such as imperfections and environmental noise. Their paper, “Nonreciprocal quantum synchronization,” is published in Nature Communications.

Many devices use components that act as one-way streets, allowing particles to travel in one direction, but almost not at all in the opposite one. These so-called nonreciprocal components are widely used in microwave and light-based systems for things such as controlling signal flow and preventing reflections.

“Nonreciprocal components enable signals to travel along desired paths, whereas they are strongly attenuated in the opposite direction,” notes Franco Nori of the RIKEN Center for Quantum Computing (RQC). “This ability finds applications ranging from signal processing to invisible cloaking.”

Quantum ‘dark modes’ no longer block phonon control, opening new paths for scalable devices

Three RIKEN researchers have demonstrated a way to stop problematic “dark modes” from squelching intriguing effects in quantum systems. This advance could help with the development of more versatile quantum devices that can be used to control the storage and transmission of quantum information. The study is published in the journal Nature Communications.

Manipulations that alter the topology of certain quantum systems known as non-Hermitian systems are attracting increasing attention, since they offer novel possibilities for manipulating particles of sound (phonons) and light (photons) as well as other excitations.

“Topological operations allow for various weird and fascinating phenomena, such as the buildup of chiral phases and the movement of phonons in one direction,” notes Franco Nori of the RIKEN Center for Quantum Computing (RQC).

Neutrinos caught on camera: Testing the first prototype of a new elementary particle detector

Some innovations in physics come from entirely new technologies, others from fresh theoretical insights. Others still take shape by bringing together existing tools in new ways, working out how to combine them to outperform other solutions. The branch of particle physics that studies weakly interacting particles—such as neutrinos and some types of dark-matter candidates—could use innovative detection approaches: technological challenges in this research area quickly become practical as well as economic, as increases in detector volume and spatial resolution improve the sensitivity to the processes producing the particles of interest. Similarly, demanding targets on instrument capability apply to the calorimeters used in collider experiments.

Three-dimensional (3D) tracking of elementary particles in large-volume, dense materials is required in most particle physics experiments. In a scintillator, this is commonly achieved through fine segmentation of the material into many smaller active units, with each unit emitting light in the visible frequency range when a charged particle passes through it. Typically, the photons produced in every active unit are collected by optical fibers and carried outside of the scintillator to the photomultiplier tubes or silicon photomultipliers used for photon counting.

In the T2K neutrino-oscillation experiment in Japan, for example, one detector boasts about two tons of sensitive volume assembled from approximately two million cubes and 60,000 fibers. Over at CERN and the Paul Scherrer Institute, the LHCb and Mu3e experiments achieve sub-millimeter spatial resolution thanks to millions of thin scintillating optical fibers. With these figures, it’s clear that the scalability of this kind of scintillator material segmentation may turn into a bottleneck when larger volumes become necessary.

Machine learning identifies catalyst ‘sweet spot’ for greener urea from waste gases

Urea is an extremely important chemical, especially for fertilizers. But, making urea is energy intensive and relies heavily on fossil fuels. However, new findings from Griffith University and the Queensland University of Technology have highlighted new ways to produce urea electrochemically, using electricity and waste gases such as carbon monoxide (CO) and nitrogen oxides (NO) instead.

The paper, “Machine Learning-Assisted Design Framework of Carbon Edge-Dominated Dual-Atom Catalysts for Urea Electrosynthesis,” has been published in ASC Nano.

“The challenge is that when CO and NO react on a catalyst, they usually don’t form urea,” said co-lead author Professor Qin Li from Griffith University.

New study bridges the worlds of classical and quantum physics

When you throw a ball in the air, the equations of classical physics will tell you exactly what path the ball will take as it falls, and when and where it will land. But if you were to squeeze that same ball down to the size of an atom or smaller, it would behave in ways beyond anything that classical physics can predict.

Or so we’ve thought.

MIT scientists have now shown that certain mathematical ideas from everyday classical physics can be used to describe the often weird and nonintuitive behavior that occurs at the quantum, subatomic scale.

On computing quantum waves exactly from classical action

The fundamental quantum postulates on the existence of a wave function, its propagation with the Schrödinger equation in theorem 3.2 and the wave collapse at a measurement in lemma 3.3 are derived from the classical theorem 2.4. Furthermore, analytic computations of the classical action are simpler than solving the Feynman path integral and potentially easier than solving the Schrödinger equation directly. In addition, theorem 3.2 is a multi-particle result.

The J classical multipaths in theorem 3.2 and lemma 3.3 are strictly determined by the initial and final conditions. In the double slit experiment, the probabilistic quantum observation results from the non-Lipschitz constraint force in the slit. For the harmonic oscillator, the Coulomb wave, the particle in the box, or the spinning particle, the initial probabilistic density distribution is classically propagated forward in time. In the EPR experiment [64,65], theorem 2.4 determines a constant angular momentum χo↑,χo↓ over time, and lemma 3.3 in turn allows a classical interpretation that the decision which spin correlation is sensed behind the filters is already taken when the particles separate.

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