2015 Impact factor 1.208
Atomic, Molecular, Optical and Plasma Physics

EPJ B Highlight - Autonomous machines edge towards greater independence

Mean error of self-taught system learning to recognise five vowels

Physicists are providing a greater level of autonomy for self-taught systems by combining how they respond to their learning as they evolve

Cars that can drive autonomously have recently made headlines. In the near future, machines that can learn autonomously will become increasingly present in our lives. The secret to efficient learning for these machines is to define an iterative process to map out the evolution of how key aspects of these systems change over time. In a study published in EPJ B, Agustín Bilen and Pablo Kaluza from Universidad Nacional de Cuyo, Mendoza, Argentina show that these smart systems can evolve autonomously to perform a specific and well-defined task over time. Applications range from nanotechnology to biological systems, such as biological signal transduction networks, genetic regulatory networks with adaptive responses, or genetic networks in which the expression level of certain genes in a network oscillates from one state to another.

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EPJ B Highlight - Potential new applications stem from controlling particles’ spin configurations

credit: Creativity103.

Physicists prove important constraints for fermion gases with spin population imbalance

Fermions are ubiquitous elementary particles. They span from electrons in metals, to protons and neutrons in nuclei and to quarks at the sub-nuclear level. Further, they possess an intrinsic degree of freedom called spin with only two possible configurations, either up or down. In a new study published in EPJ B, theoretical physicists explore the possibility of separately controlling the up and down spin populations of a group of interacting fermions. Their detailed theory describing the spin population imbalance could be relevant, for instance, to the field of spintronics, which exploits polarised spin populations.

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EPJB Colloquium: The continuous-time random walk, fifty years on

This Colloquium paper published in EPJ B by R. Kutner and J. Masoliver revisits the most significant achievements and future possibilities for continuous-time random walk (CTRW), a versatile and widely applied formalism.

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EPJ B Highlight - The secrets of vibration-enhanced conductivity in graphene

Graphene structure. The transverse short-wavelength vibrational mode is excited by applying initial displacements to the atoms of the red and blue sublattices in opposite directions along the Z axis.

Physicists define a smart way of inducing large-amplitude vibrations in graphene models, which could open the door for novel electronic applications

Graphene, the one-atom-thick material made of carbon atoms, still holds some unexplained qualities, which are important in connection with electronic applications where high-conductivity matters, ranging from smart materials that collectively respond to external stimuli in a coherent, tunable fashion, to light-induced, all-optical networks. Materials like graphene can exhibit a particular type of large-amplitude, stable vibrational modes that are localised, referred to as Discrete Breathers (DBs). The secret to enhancing conductivity by creating DBs lies in creating the external constraints to make atoms within the material oscillate perpendicular to the direction of the graphene sheet. Simulations-based models describing what happens at the atomic level are not straightforward, making it necessary to determine the initial conditions leading to the emergence of DBs. In a new paper published in EPJ B, Elham Barani from the Ferdowsi University of Mashhad, Iran, and colleagues from Russia, Iran and Singapore use a systematic approach to identify the initial conditions that lend themselves to exciting DBs in graphene, ultimately opening the door to understanding the keys to greater conductivity.

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EPJ B Highlight - Tortoise electrons trying to catch up with hare photons give graphene its conductivity

Illustrative picture of the system studied.

Collective electron interaction, mediated by photons across space-time under a weak magnetic field, explains the special conductivity of the one-atom-thick material

How electrons interact with other electrons at quantum scale in graphene affects how quickly they travel in the material, leading to its high conductivity. Now, Natália Menezes and Cristiane Morais Smith from the Centre for Extreme Matter and Emergent Phenomena at Utrecht University, the Netherlands, and a Brazilian colleague, Van Sergio Alves, have developed a model attributing the greater conductivity in graphene to the accelerating effect of electrons interacting with photons under a weak magnetic field. Their findings have been published in EPJ B.

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EPJ B Highlight - When crystal vibrations‘ inner clock drives superconductivity

Superconductor. © ktsdesign/Fotolia

Tweaking equations to drive greater superconductivity-inducing crystal vibrations proves theoretical possibility of creating higher temperature superconductors

Superconductivity is like an Eldorado for electrons, as they flow without resistance through a conductor. However, it only occurs below a very low critical temperature. Physicists now believe they can enhance superconductivity - the idea is to externally drive its underlying physical phenomena by changing how ions vibrating in the crystal lattice of the conductor material, called phonons, interact with electron flowing in the material. Andreas Komnik from the University of Heidelberg and Michael Thorwart from the University of Hamburg, Germany, adapted the simplest theory of superconductivity to reflect the consequences of externally driving the occurrence of phonons. Their main result, published in EPJ B, is a simple formula explaining how it is theoretically possible to raise the critical temperature using phonon driving.

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EPJ B Special issue dedicated to the Volker Heine Award

EPJ B, in partnership with the Ψk conference, is honoured to introduce this monthly issue with five articles written by the finalists of the Volker Heine Award 2015.

The Ψk conference is the foremost event in the field of electronic structure and computation in condensed matter, and the Volker Heine award is one of its highlights. Being intended for young researchers, the award aims at helping their career by exposing their work in a prestigious international conference, and adding a modest point to their Curriculum Vitae.

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EPJ B Colloquium: First-principles dynamics of electrons and phonons

Feynman diagram for the phonon-electron scattering process

First-principles calculations combining density functional theory and many-body perturbation theory can provide microscopic insight into the dynamics of electrons and phonons in materials. In this EPJ B Colloquium, Marco Bernardi, winner of the Psi’K young investigator award, reviews this theoretical and computational framework, focusing on perturbative treatments of scattering, dynamics, and transport of electrons and phonons. The article examines applications of these first-principles calculations in electronics, lighting, spectroscopy, and renewable energy.

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EPJ B Highlight - Supersonic phenomena, the key to extremely low heat loss nano-electronics

Low-frequency pinned discrete breather when the on-site interaction largely overwhelms the inter-site force.

Supersonic solitary waves in nano-electronics crystals show potentials for electric charge or matter transport and energy storage with extremely low heat dissipation

Freak waves, as well as other less striking localised excitations, occur in nature at every scale. The current theory and models of such waves can be applied to physics and, among others, to oceanography, nonlinear optics and lasers, acoustics, plasmas, cosmological relativity and neuro-dynamics. However, they could also play a significant role at the quantum scale in nano-electronics. In a recent study, Manuel G. Velarde from the Pluridisciplinary Institute of the University Complutense of Madrid, Spain, and colleagues, performed computer simulations to compare two types of localised excitations in nano-electronics. Their findings, published in a recent study in EPJ B, confirm that such localised excitations are natural candidates for energy storage and transport. These, in turn, could lead to applications such as transistors with extremely low heat dissipation not using silicon.

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EPJ B Highlight - New method helps stabilise materials with elusive magnetism

Visualisation of itinerant ferromagnetic domains.

Stabilising materials with transient magnetic characteristics makes it easier to study them

Magnetic materials displaying what is referred to as itinerant ferromagnetism are in an elusive physical state that is not yet fully understood. They behave like a magnets under very specific conditions, such as at ultracold temperatures near absolute zero. Physicists normally have no other choice than to study this very unique state of matter in a controlled fashion, using ultracold atomic gases. Now, a team based at ETH Zurich, Switzerland has introduced two new theoretical approaches to stabilise the ferromagnetic state in quantum gases to help study the characteristics of itinerant ferromagnetic materials. These results were recently published in EPJ B by Ilia Zintchenko and colleagues.

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Editors-in-Chief
V. Buzek, H. Kersten and A.V. Solov'yov
It was a pleasure to collaborate with your journal as a referee. Also in the future I will be pleased to do this again.

Tomaz Gyergyek

ISSN (Print Edition): 1434-6060
ISSN (Electronic Edition): 1434-6079

© EDP Sciences, Società Italiana di Fisica and Springer-Verlag

Conference announcements

POSMOL 2017

Magnetic Island, Queensland, Australia, 22-24 July 2017