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Historical Perspectives on Contemporary Physics


EPJ D Topical Issue: Precision Physics of Simple Atomic Systems

Guest Editors: Krzysztof Pachucki, Thomas Udem, Wim Ubachs, Paolo Crivelli & Stefan Ulmer

This EPJD special issue dedicated to the field of precision physics of simple atomic systems includes several important peer-reviewed contributions, presented on the 11th edition of the PSAS conference —initially planned to take place in May 2020 in Wuhan, China (only to be rescheduled 2 years later, in May 2022, due to the COVID-19 pandemic, in Warsaw, Poland).

The aim of the PSAS conference is to gather scientists from all over the world working on precise calculations and measurements, with the goal to test fundamental physics, to verify laws of physics, and to determine fundamental constants. Correspondingly, a mix of theoretical, numerical and experimental works spanning the fields of spectroscopy of atomic and molecular hydrogen, QED of few-electron bound systems, exotic atoms and ions, searches for BSM physics with atoms and antimatter, clocks, measurements of g-2 and alpha, originating from several of the major groups in this field, are reported here, making the current collection of interest for both the younger generation entering this research field and experts for efficient access on recent developments.

All articles are available here and are freely accessible until 29 August 2023. For further information read the Editorial.

EPJ D Highlight - Testing a perfect absorber metamaterial

The schematic picture of a proposed perfect absorber metamaterial

The proposed metamaterial could have a wide range of applications, from sensing to stealth technology

Metamaterials are a type of artificial material which, as the prefix “meta” – meaning in Greek “after” or “beyond” – indicates, demonstrate electromagnetic properties and other characteristics not found in nature.

As a result of these characteristics, including negative refraction and perfect lensing and cloaking, which arise from the lattice design composition of these substances rather than the materials that actually comprise them, metamaterials have become a hot research topic.

In particular, materials scientists are actively hunting for metamaterials that are “perfect absorbers” of electromagnetic radiation with controllable resonance characteristics that lead to their wide usage in applications as varied as solar cells, thermal radiation imaging, sensing technology, and even stealth technology.

In a new paper in EPJ D, Shahzad Anwar, a researcher at the Department of Physics, Islamia College Peshawar, Pakistan, and his colleagues document the proposed design of a triple-band perfect metamaterial absorber. The new metamaterial could have applications in sensors, filters, and in stealth technology.


EPJ D Highlight - A broader approach to quantum walks

Simulating an evolving quantum system

Quantum walks have been widely studied for their ability to simulate real physical phenomena. Physicists previously studied two distinct types of quantum walk, but so far, they haven’t widely considered how their mathematical descriptions could be linked. Through new research published in EPJ D, a pair of physicists in France: Nicolas Jolly at ENS de Lyon, and Giuseppe Di Molfetta at Aix-Marseille University, show how ‘discrete-‘ and ‘continuous-time’ quantum walks can be described using more general mathematical language. Their results could allow researchers to simulate an even broader range of phenomena using quantum walks.


EPJ E Highlight - Steering ‘microswimmers’ through choppy waters

A diagram of microswimmers immersed in a non-steady flow following five possible navigation strategies. Credit: J. Bec (2023)

New research looks at navigation strategies for deformable microswimmers in a viscous fluid faced with drifts, strains, and other deformations.

A deformable microswimmer is a small-scale organism or artificial structure that uses sinusoidal body undulations to propel itself through a fluid environment.

The term applies to organisms like bacteria which navigate through fluids using whip-like tails called flagella, sperm cells propelling themselves through the female reproductive system, and even nematodes, tiny worms that move through water or soil with undulations. Microswimmers can also describe tiny microrobots constructed from soft-materials designed to respond to stimuli and perform tasks like drug delivery on a micro-scale.

That means the study of microswimmers has applications in a vast array of scientific fields, from biology to fundamental physics to nanorobotics.

In a new paper in EPJ E by Jérémie Bec, a researcher at CNRS and Centre Inria d’Université Côte d’Azur and his colleagues attempt to find an optimal navigation policy for microswimmers, crucial for enhancing their performance, functionality, and versatility for applications such as targeted drug delivery.


EPJ H Highlight - Is the end of the “particle era” of physics upon us?

The completed standard model of particle physics. What shape will physics beyond this model take? Credit: Daniel Dominguez/CERN

New research looks at the potential for new discoveries in particle physics

The discovery of the Higgs Boson in 2012 represented a major turning point for particle physics marking the completion of what is known as the standard model of particle physics. Yet, the standard model can’t answer every question in physics, thus, since this discovery at the Large Hadron Collider (LHC) physicists have searched for physics beyond the standard model and to determine what shape future physics will take.

A new paper in EPJ H: Historical Perspectives on Contemporary Physics by Robert Harlander and Jean-Philippe Martinez of the Institute for Theoretical Particle Physics and Cosmology, RWTH Aachen University, Germany, and Gregor Schiemann from the Faculty of Humanities and Cultural Studies, Bergische Universität Wuppertal, Germany, considers the idea that particle physics may be on the verge of a new era of discovery and understanding in particle physics. The paper also considers the implications of the many possible scenarios for the future of high-energy physics.


EPJ D Topical Issue: Dynamics of Systems on the Nanoscale (2021)

Guest Editors: Alexey V. Verkhovtsev, Vincenzo Guidi, Nigel J. Mason, Andrey V. Solov’yov

Understanding the Dynamics of Systems on the Nanoscale forms the core of a multidisciplinary research area addressing many challenging interdisciplinary problems at the interface of physics, chemistry, biology, and materials science. They include problems of structure formation, fusion and fission, collision and fragmentation, surfaces and interfaces, collective electronic excitations, reactivity, nanoscale phase and morphological transitions, irradiation driven transformations of complex molecular systems, biodamage, channeling phenomena, and many more. Common to these interdisciplinary scientific problems is the central role of the structure formation and dynamics of animate and inanimate matter on the nanometer scale.

This topical issue presents a collection of research papers devoted to different aspects of the Dynamics of Systems on the Nanoscale, ranging from fundamental research on elementary atomic and molecular mechanisms to studies at a more applied level, covering innovative theoretical, experimental and computational modeling techniques. Some of the contributions discuss specific applications of the research results in several modern and emerging technologies, such as controlled nanofabrication with charged particle beams or the design and practical realization of novel gamma-ray crystal-based light sources.


EPJ B Highlight - Investigating the use of noise to solve inverse physical problems

A graphical representation of a seismic inversion problem. Credit: Corso, et al, (2023)

New research looks at the problem of solving a physics problem starting with observational data and working backwards

The early success of physics comes mainly from solving direct or forward problems in which the physical state of a system can be described from a well-defined physical model and from governing equations. Yet, there exists a different type of problem, inverse problems, that are trickier to solve but are crucial to fields such as engineering, astrophysics and geophysics.

Solving these inverse problems requires taking a set of observational data and then working backwards, or inverting the problem, to arrive at the causal factors that gave rise to the data.

A new paper in EPJ B by Universidade Federal do Rio researchers Gilberto Corso and João Medeiros de Araujo, considers the possibility of solving inverse problems in physics by using statistical information from noise statistics.


EPJ B Highlight - Uncovering spin ladders in real compounds

Ladder in a low-dimensional spin system

Low-dimensional quantum systems named ‘spin ladders’ are strongly linked to superconductivity. A new theoretical approach has accurately predicted the nature of the spin ladder which appears in real chemical compound – possibly paving the way for new discoveries of advanced superconductors.

When fabricated in 1 or 2 dimensions, systems of particles whose quantum spins interact with each other can display some unique quantum properties. Through new research published in EPJ B, Asif Iqbal and Baidur Rahaman at Aliah University in Kolkata, India, developed a new theoretical technique for calculating the structures and interactions taking place in these unique materials. Their approach could pave the way for advanced new superconductors – which allow electric currents to flow through them with zero resistance.


EPJ E Highlight - Active Brownian particles have four distinct states of motion

Switching between locked and running states

Depending on the friction and external bias forces they experience, self-propelled Brownian particles will take on one of four possible states of motion. The discovery could help researchers to draw deeper insights into the behaviours of these unique systems in nature and technology.

Active Brownian motion describes particles which can propel themselves forwards, while still being subjected to random Brownian motions as they are jostled around by their neighbouring particles. Through new analysis published in EPJ E, Meng Su at Northwestern Polytechnical University in China, together with Benjamin Lindner at Humboldt University of Berlin, Germany, have discovered that these motions can be accurately described using four distinct mathematical patterns.


EPJ Data Science Highlight - Investigating gender equality in urban cycling

An overview of the gender gap in recreational cycling across cities included in the study according to Strava. Credit: A. Battison et al. (2023)

New research looks at why cycling has a low uptake among women in urban areas

Over recent years not only has cycling proved itself to be an outdoor activity with tremendous health benefits, but it has also presented itself as a useful tool in the quest to find an environmentally friendly method of urban transportation.

Despite the increasing popularity of cycling, many countries still have a negligible uptake in the pursuit and this is even more pronounced when considering how many women engage in cycling. To this day, a mostly unexplained gender gap exists in cycling.

A new paper in EPJ Data Science by the University of Turin Department of Computer Science researcher Alice Battiston and her co-authors attempts to understand the determinants behind the gender gap in cycling on a large scale.


M. Eckert and J.D. Wells
ISSN (Print Edition): 2102-6459
ISSN (Electronic Edition): 2102-6467

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