EPJ D Colloquium - Overview of photo-neutralization techniques for negative ion-based neutral beam injectors in future fusion reactors

The need for safe, carbon-free and abundant sources of energy is becoming more and more pressing. While still under development, nuclear fusion can play a key role in a medium term, decarbonized energy scenario. However, in order for fusion to be commercially competitive, many sub-systems constituting the current experimental reactors need to be optimized in terms of their efficiency: in particular, DEMO and future fusion energy plants will require a substantial increase in the energy performances of the plasma heating systems.


EPJ E Highlight - Considering how friction is maximised when liquids flow on nanoscales

A cross-section of simulations of several different flow types with pistons placed at different positions. Credit: S. Chen et al, 2022

By simulating a liquid confined by a nanoscale structure, researchers discovered the role molecular clogging plays in friction.

The dynamics of how liquids behave when confined in a nanoscale-sized space such as nanochannels, nanotubes or nanopores, is key to understanding a wealth of processes including lubrication, filtration and even energy storage.

The dynamics of liquids at nanoscales are different to behaviour in confinement at macroscales, however. One of the key differences that a reduction in scale creates is friction and shear between the liquid and its solid container. And further complications arise in systems with solid-to-solid contact with features like wear, micro-pitting and scuffing created.

A new paper published in EPJ E and authored by Shan Chen, from the State Key Laboratory of Organic-Inorganic Composites at Beijing University of Chemical Technology, China, uses simulations of molecular dynamics to look at the friction-induced nano-confined liquids.


EPJ B Highlight - Assessing the effect of hydraulic fracturing on microearthquakes

A cross-section of a hydrofracturing site showing preconditioning by blasting. Credit: de la Barra. E., et al, [2022]

New research examines mining sites with hydraulic fracturing comparing it to those without to determine the practice’s effect on seismic hazards.

The analysis of low-intensity human-caused microearthquakes, including their magnitude and frequency, has become an important factor in mining. This is a consideration not only for the safety of mining staff, but also for extraction rates and mine stability that can have major impacts on business performance. Increasingly, the practice of hydraulic fracturing is used to precondition mines and diminish the magnitude of induced tremors as well as reduce the number of rock fragments extracted.

A new paper published in EPJ B assesses the impact of hydraulic fracturing on seismic hazards like microearthquakes, an important issue for the safety of workers and the continuation of mining operations. The paper is authored by Erick de la Barra, Pedro Vega-Jorquera and Héctor Torres from the University of La Serena, Chile, alongside Sérgio Luiz E. F. da Silva from Politecnico di Torino, Department of Applied Science and Technology, Turin, Italy.


EPJ H Highlight - A step towards quantum gravity

Representation of the Earth affecting the curvature of spacetime. File:Spacetime_lattice_analogy.svg Mysid, CC BY-SA 3.0.

Resolving the problem of time

In Einstein’s theory of general relativity, gravity arises when a massive object distorts the fabric of spacetime the way a ball sinks into a piece of stretched cloth. Solving Einstein’s equations by using quantities that apply across all space and time coordinates could enable physicists to eventually find their ‘white whale’: a quantum theory of gravity. In a new article in EPJ H: Historical Perspectives on Contemporary Physics, Donald Salisbury from Austin College in Sherman, USA, explains how Peter Bergmann and Arthur Komar first proposed a way to get one step closer to this goal by using Hamilton-Jacobi techniques. These arose in the study of particle motion in order to obtain the complete set of solutions from a single function of particle position and constants of the motion.


Luís Carlos joins the EPJ Scientific Advisory Committee (SAC)

Luís Carlos

The Scientific Advisory Committee of EPJ is delighted to welcome Prof. Luís Carlos as the new representative for the Portuguese Physical Society.

Luís D. Carlos is a full professor at the University of Aveiro, Portugal, where he works in the field of optical materials, luminescence nanothermometry and applications of organic-inorganic hybrids in luminescent solar concentrators, solid-state lighting, and integrated optics

EPJ QT Highlight - Quantum control for advanced technology: Past and present

A new review lays out a roadmap for quantum technologies. Credit: Robert Lea

Quantum devices are a promising technological advance for the future, but this will hinge on the application of quantum optimal control top real-world devices. A new review looks at the status of the field as it stands.

One of the cornerstones of the implementation of quantum technology is the creation and manipulation of the shape of external fields that can optimise the performance of quantum devices. Known as quantum optimal control, this set of methods comprises a field that has rapidly evolved and expanded over recent years.

A new review paper published in EPJ Quantum Technology and authored by Christiane P. Koch, Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin along with colleagues from across Europe assesses recent progress in the understanding of the controllability of quantum systems as well as the application of quantum control to quantum technologies. As such, it lays out a potential roadmap for future technology.


EPJ TI Highlight - QEMMS: Improving measurements of the kilogram

The QEMMS mechanism

Currently in development by NIST, QEMMS will allow researchers to measure macroscopic masses, based on quantum principles. New analysis shows how an optimised design of this device could significantly reduce the errors associated with current approaches to mass measurement.

Until 2018, the SI unit of mass, the kilogram, was defined as the mass of a real object: the International Prototype Kilogram, kept in a secure facility in the outskirts of Paris. On November 16, 2018, the kilogram was given a new, internationally-accepted definition, based on three defining constants: the speed of light, the Planck constant, and the hyperfine transition frequency of caesium. One of the methods to measure a mass based on the new definition is a device named the Kibble balance.

Despite the current precision of this device’s measurements, its components can be improved to reduce sources of uncertainties. Through new research published in EPJ Techniques and Instrumentation, Darine Haddad and colleagues at the National Institute of Standards and Technology (NIST) show how a new, optimised approach to the Kibble balance’s design could further improve its accuracy.


EPJ ST Highlight - Chaotic circuit exhibits unprecedented equilibrium properties

Mapping chaotic oscillations.

Mathematical derivations have unveiled a chaotic, memristor-based circuit in which different oscillating phases can co-exist along 6 possible lines.

Unlike ordinary electronic circuits, chaotic circuits can produce oscillating electrical signals which never repeat over time – but nonetheless, display underlying mathematical patterns. To expand the potential applications of these circuits, previous studies have designed systems in which multiple oscillating phases can co-exist along mathematically-defined ‘lines of equilibrium.’ In new research published in EPJ ST, a team led by Janarthanan Ramadoss at the Chennai Institute of Technology, India, designed a chaotic circuit with six distinct lines of equilibrium – more than have ever been demonstrated previously.


EPJ B Highlight - Bringing consistency to methods of 2D material analysis

A sheet of 2D material-graphene-curved to create a nanotube. Credit: Michael Ströck (CC by SA 3.0)

New research introduces a more cohesive approach to the functional renormalization group — a key tool in the analysis of 2D materials

In materials science, the term “2D materials” refers to crystalline solids that consist of a single layer of atoms, with arguably the most famous example being graphene — a material made of a single layer of carbon atoms. These materials are promising for a wide range of applications including in sophisticated electronics and quantum computing thanks to their unique quantum properties.

One of the most promising methods of investigating these materials, and specifically their temperature instabilities, and for investigating quantum many-body phenomena is the functional renormalisation group (FRG). Yet, despite significant efforts, no systematic and comprehensive cohesion exists for different momentum space FRG implementations.

A new paper published in EPJ B and authored by Jacob Beyer, Institute for Theoretical Solid State Physics, RWTH Aachen University, Germany, alongside Jonas B. Hauck, and Lennart Klebl of the university’s Institute for Theory of Statistical Physics lays out a potential groundwork for achieving consistency across FRG methods.


EPJ ST Highlight - The fascinating ways animals navigate

Desert ant Cataglyphis returns directly to its nest after finding food.

Many animals – from birds to whales to zebras – find their way across great distances using a variety of environmental factors.

The Arctic Tern migrates an extraordinarily long way – from pole to pole. And while this bird is unique in the distance it traverses, its excellent sense of direction is shared by many other animals that use a variety of environmental factors to optimise their routes. In a new review paper in EPJ ST, Roswitha and Wolfgang Wiltschko from the Goethe-Universität in Frankfurt am Main, Germany, outline how animals use internal compasses to navigate and the mechanisms they are likely to use to determine the direction of their destination. These can be applied when developing effective navigation systems for robots.


Pere Roca i Cabarrocas and Daniel Lincot
ISSN: 2105-0716 (Electronic Edition)

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