Europhysics Letters - IOPscience

Europhysics Letters - IOPscience
The European Physical Society (EPS)
is a not for profit association whose members include 41 National Physical Societies in Europe, individuals from all fields of physics, and European research institutions.
As a learned society, the EPS engages in activities that strengthen ties among the physicists in Europe. As a federation of National Physical Societies, the EPS studies issues of concern to all European countries relating to physics research, science policy and education.
Italian Physical Society
EDP Sciences
The Institute of Physics (IOP)
is a leading scientific society promoting physics and bringing physicists together for the benefit of all. It has a worldwide membership of around 50 000 comprising physicists from all sectors, as well as those with an interest in physics. It works to advance physics research, application and education; and engages with policy makers and the public to develop awareness and understanding of physics. Its publishing company, IOP Publishing, is a world leader in professional scientific communications.
ISSN:
1286-4854
SUPPORTS OPEN ACCESS
A Letters journal serving all areas of physics and its related fields,
EPL
publishes the highest quality research from around the world, and provides authors with fast, fair and constructive peer review thanks to an Editorial Board of active scientists, who are experts in their respective fields.
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2024 Impact factor
1.8
Citescore
3.5
The following article is
Open access
The non-Hermitian skin effect: A perspective
Julius T. Gohsrich
et al
2025
EPL
150
60001
View article
, The non-Hermitian skin effect: A perspective
PDF
, The non-Hermitian skin effect: A perspective
The non-Hermitian (NH) skin effect is a truly NH feature, which manifests itself as an accumulation of states, known as skin states, on the boundaries of a system. In this perspective, we discuss several aspects of the NH skin effect focusing on the most interesting facets of this phenomenon. Beyond reviewing necessary requirements to see the NH skin effect, we discuss the NH skin effect as a topological effect that can be seen as a manifestation of a truly NH bulk-boundary correspondence, stemming from the spectral topology, and show how skin states can be distinguished from topological boundary states. As most theoretical work has focused on studying the NH skin effect in one-dimensional non-interacting systems, recent developments of studying this effect in higher dimensions as well as in many-body systems are highlighted. Lastly, experimental signatures and applications are discussed, and an outlook is provided.
The following article is
Open access
Towards animate droplets: Active, adaptive, and autonomous
Joe Forth
et al
2026
EPL
153
57002
View article
, Towards animate droplets: Active, adaptive, and autonomous
PDF
, Towards animate droplets: Active, adaptive, and autonomous
Droplets, sub-millilitre liquid volumes with at least one interface, have traditionally served as compartments for storing, transporting, and delivering materials. Beyond familiar applications in food, coatings, and consumer goods, they find cutting-edge use in energy storage, sensing, and tissue engineering. The next frontier is their integration into animate matter, emerging materials defined by their levels of activity, adaptiveness, and autonomy. Easy to produce and dispense or print into complex structures, and with enormous chemical versatility, droplets are ideal building blocks for animate matter. In this Perspective, we outline a roadmap for advancing animacy in droplets and call for a more concerted effort to integrate novel mechanisms for motility, sensing, and decision-making into droplet design. Although research on active droplets spans more than a century, achieving true autonomy, where droplets process multiple stimuli and respond without external control, remains a central challenge. We hope to inspire interdisciplinary collaboration towards applications in microfluidics, adaptive optics, tissue engineering, and soft robotics.
The following article is
Open access
On the physical origin of the fine-structure constant
L. Varani
et al
2026
EPL
153
30001
View article
, On the physical origin of the fine-structure constant
PDF
, On the physical origin of the fine-structure constant
The fine-structure constant
is a dimensionless constant introduced by sommerfeld in 1916. This number was interpreted as a way of quantifying the strength of the electromagnetic interaction. Since then, several physicists expressed their dissatisfaction waiting for a more direct interpretation. Here we propose a one-to-one correspondence between
and the variance of the photon number
inside a black-body of given volume and temperature. As a broader perspective we propose that any atomic spectral-line is associated with a line-structure constant that provides the macroscopic statistical information on the photon gas inside the corresponding black-body cubic cavity. From this point of view, the expression of the Sommerfeld constant is considered as a particular case that coincides exactly with our results when the black-body temperature corresponds to the equivalent temperature of the emission line of
and with the cubic size of the black body
The following article is
Open access
Three-dimensional contractile droplet under confinement
A. Tiribocchi
et al
2026
EPL
154
17001
View article
, Three-dimensional contractile droplet under confinement
PDF
, Three-dimensional contractile droplet under confinement
We numerically study the dynamics of a three-dimensional contractile fluid droplet in the bulk and under confinement. We show that varying activity leads to a variety of shapes and motile regimes whose motion is driven by an interplay between spontaneous flows and elasticity. In the bulk the droplet self-propels unidirectionally, acquiring either an almost spherical shape at intermediate activity or a peanut-like geometry for larger values. Under confinement, the droplet exhibits a previously unreported oscillating dynamics characterized by periodic hits against opposite walls of a microchannel while moving forward. These results could be of interest for the study of artificial microswimmers and their biological analogs, such as living cells.
Machine learning in physics: A short guide
Francisco A. Rodrigues 2023
EPL
144
22001
View article
, Machine learning in physics: A short guide
PDF
, Machine learning in physics: A short guide
Machine learning is a rapidly growing field with the potential to revolutionize many areas of science, including physics. This review provides a brief overview of machine learning in physics, covering the main concepts of supervised, unsupervised, and reinforcement learning, as well as more specialized topics such as causal inference, symbolic regression, and deep learning. We present some of the principal applications of machine learning in physics and discuss the associated challenges and perspectives.
Erratum: When are active Brownian particles and run-and-tumble particles equivalent? Consequences for motility-induced phase separation
M. E. Cates and J. Tailleur 2026
EPL
154
19902
View article
, Erratum: When are active Brownian particles and run-and-tumble particles equivalent? Consequences for motility-induced phase separation
PDF
, Erratum: When are active Brownian particles and run-and-tumble particles equivalent? Consequences for motility-induced phase separation
Original article:
EPL
101
(2013) 20010
Orbitronics: Orbital currents in solids
Dongwook Go
et al
2021
EPL
135
37001
View article
, Orbitronics: Orbital currents in solids
PDF
, Orbitronics: Orbital currents in solids
In solids, electronic Bloch states are formed by atomic orbitals. While it is natural to expect that orbital composition and information about Bloch states can be manipulated and transported, in analogy to the spin degree of freedom extensively studied in past decades, it has been assumed that orbital quenching by the crystal field prevents significant dynamics of orbital degrees of freedom. However, recent studies reveal that an orbital current, given by the flow of electrons with a finite orbital angular momentum, can be electrically generated and transported in wide classes of materials despite the effect of orbital quenching in the ground state. Orbital currents also play a fundamental role in the mechanisms of other transport phenomena such as spin Hall effect and valley Hall effect. Most importantly, it has been proposed that orbital currents can be used to induce magnetization dynamics, which is one of the most pivotal and explored aspects of magnetism. Here, we give an overview of recent progress and the current status of research on orbital currents. We review proposed physical mechanisms for generating orbital currents and discuss candidate materials where orbital currents are manifest. We review recent experiments on orbital current generation and transport and discuss various experimental methods to quantify this elusive object at the heart of
orbitronics
—an area which exploits the orbital degree of freedom as an information carrier in solid-state devices.
Remarks to the Comment by J. R. Bray and M. C. Britton on “Observation of scalar longitudinal electrodynamic waves”
C. Monstein and J. P. Wesley 2004
EPL
66
155
View article
, Remarks to the Comment by J. R. Bray and M. C. Britton on “Observation of scalar longitudinal electrodynamic waves”
PDF
, Remarks to the Comment by J. R. Bray and M. C. Britton on “Observation of scalar longitudinal electrodynamic waves”
Dynamics of Dzyaloshinskii domain walls in ultrathin magnetic films
André Thiaville
et al
2012
EPL
100
57002
View article
, Dynamics of Dzyaloshinskii domain walls in ultrathin magnetic films
PDF
, Dynamics of Dzyaloshinskii domain walls in ultrathin magnetic films
We explore a new type of domain wall structure in ultrathin films with perpendicular anisotropy, that is influenced by the Dzyaloshinskii-Moriya interaction due to the adjacent layers. This study is performed by numerical and analytical micromagnetics. We show that these walls can behave like Néel walls with very high stability, moving in stationary conditions at large velocities under large fields. We discuss the relevance of such walls, that we propose to call Dzyaloshinskii domain walls, for current-driven domain wall motion under the spin Hall effect.
The following article is
Open access
Chiral active matter
Benno Liebchen and Demian Levis 2022
EPL
139
67001
View article
, Chiral active matter
PDF
, Chiral active matter
Chiral active matter comprises particles which can self-propel and self-rotate. Examples range from sperm cells and bacteria near walls to autophoretic L-shaped colloids. In this perspective article we focus on recent developments in chiral active matter. After briefly discussing the motion of single particles, we discuss collective phenomena ranging from vortex arrays and patterns made of rotating micro-flocks to states featuring unusual rheological properties.
Combined with failure propagation model, the importance evaluation and critical node identification of five functional nodes of combat system are presented
Jiangpeng Wang and Ping Yang 2026
EPL
154
22002
View article
, Combined with failure propagation model, the importance evaluation and critical node identification of five functional nodes of combat system are presented
PDF
, Combined with failure propagation model, the importance evaluation and critical node identification of five functional nodes of combat system are presented
To address node heterogeneity, complex functional dependences, and the limited ability of traditional metrics to capture system-level failure impacts in combat networks, this paper proposes a node-importance evaluation and critical-node identification method that couples failure propagation modeling with flow-blockage theory. We first construct a directed heterogeneous network with five functional node types and explicitly define their resource interfaces and dependency paths. An improved threshold-based propagation mechanism and a composite influence function integrating propagation probability, neighbor overlap, and the KHC topological index are then introduced, and a propagation-efficiency coupled identification algorithm is developed using the max-flow/min-cut principle to quantify traffic degradation under failures. Simulations across multiple failure scenarios and network topologies show that the proposed method significantly outperforms conventional centrality measures in identifying system-level high-loss nodes, yielding more actionable, task-chain–focused results with strong adaptability and robustness. These findings provide theoretical and algorithmic support for combat-network vulnerability assessment, resilient command-system design, and suppression-path planning.
The following article is
Open access
Rayleigh-Bénard thermal convection in emulsions: A short review
F. Pelusi
et al
2026
EPL
154
23001
View article
, Rayleigh-Bénard thermal convection in emulsions: A short review
PDF
, Rayleigh-Bénard thermal convection in emulsions: A short review
Thermally driven emulsions arise in a broad range of natural and industrial contexts, yet their fundamental physical understanding remains only partially established. Emulsions exhibit a complex, concentration-dependent rheology, ranging from Newtonian (dilute emulsions) to yield stress (concentrated emulsions). In buoyancy-driven flows, the complex structure and rheology of the emulsion are strongly coupled to convective flows, giving rise to fascinating and non-trivial phenomena involving stability, transient dynamics, and morphological evolution of the system. We review recent progress on thermally driven emulsions in the celebrated Rayleigh-Bénard configuration, offering new perspectives on the behaviour of soft materials in thermal convection.
Hydrogenation-induced superconductivity in 2H-V
N MXene monolayer
Jing-Hua Wang
et al
2026
EPL
154
26001
View article
, Hydrogenation-induced superconductivity in 2H-V2N MXene monolayer
PDF
, Hydrogenation-induced superconductivity in 2H-V2N MXene monolayer
We investigated the structural, electronic, dynamical, and superconducting properties of hydrogenated 2H-V
N (V
NH
) using first-principles calculations. The results show that 2H-V
NH
is dynamically stable and an anisotropic superconductor. Hydrogenation enhances electron-phonon coupling. The electronic states near the Fermi level are dominated by V-3
orbitals. Electron-phonon coupling calculations yield a coupling constant
= 0.70, originating mainly from low-frequency vibrations of V atoms. Anisotropic Migdal-Eliashberg calculations predict a superconducting critical temperature of 20.2 K, which is comparatively high among theoretically predicted superconducting MXenes and approximately 1.6 times the isotropic Allen-Dynes result (12.8 K ). Our results provide theoretical guidance for the design of MXene superconductors.
The following article is
Open access
On the importance of stochasticity in closures of turbulence
A. Freitas
et al
2026
EPL
154
23002
View article
, On the importance of stochasticity in closures of turbulence
PDF
, On the importance of stochasticity in closures of turbulence
Deterministic closures for coarse-grained turbulence models help reproduce mean statistics, but often fail to capture the finite-time growth of uncertainty. Using the framework of shell models as a quantitative multi-scale testbed, we compare fully resolved simulations with large-eddy simulations using either stochastic or deterministic subgrid closures. While in the fully resolved system a single microscopic perturbation is rapidly amplified by strongly chaotic dynamics, truncation produces a strong delay and suppression of variance growth when uncertainty is introduced through initial condition perturbations only. We show that a data-driven Langevin-type stochastic closure restores the correct timing and magnitude of variance growth across scales, demonstrating that sustained stochasticity is essential for predictability in reduced turbulent dynamics.
Magnetized vortex in three-dimensional
) gravity
F. C. E. Lima 2026
EPL
154
22003
View article
, Magnetized vortex in three-dimensional f(R) gravity
PDF
, Magnetized vortex in three-dimensional f(R) gravity
Modified Gravity Theories (MGTs) are extensions of General Relativity (GR) in its standard formulation. Therefore, within this framework, we will investigate a system composed of a black hole (BH) surrounded by Maxwell-Higgs vortices, forming the BH-vortex system. In the case of linear
) gravity it is adopted showing the existence of a three-dimensional ring-like BH-vortex system with quantized magnetic flux. Within this system, one notes the BH at
= 0 and its event horizon at
, while the magnetic vortices are at
. A remarkable result is the constancy of the Bekenstein-Hawking temperature (
), regardless of MGTs and vortex parameters. This invariance of
suggests that the BH-vortex system reaches thermodynamic stability. Unlike the standard theory of Maxwell-Higgs vortices in flat spacetime, in
) gravity, the vortices suffer the influence of the BH's event horizon. This interaction induces perturbations in the magnetic vortex profile, forming cosmological ring-like magnetic structures.
On the gravitational angular momentum of axial perturbations of a regular black hole
Ulhoa et al
View accepted manuscript
, On the gravitational angular momentum of axial perturbations of a regular black hole
PDF
, On the gravitational angular momentum of axial perturbations of a regular black hole
This Letter deals with the gravitational angular momentum carried by axial (odd-parity) perturbations of the Bardeen regular black hole within the teleparallel equivalent of general relativity (TEGR). Using the Hamiltonian definition of conserved quantities in TEGR, we derive a closed expression for the perturbative angular momentum $\delta J$ in terms of the axial perturbation function $h_0(r,t)$. The result exhibits a sharp multipolar selection rule: $\delta J$ vanishes for odd values of the multipole index $\ell$, while even-$\ell$ modes yield a nonzero contribution. The radial and temporal behavior of $\delta J$ is illustrated using the known axial quasinormal modes of the Bardeen spacetime.
Bias voltage-tunable existence boundaries of phononic frequency combs in nonlinear mechanical resonators based on 2D materials - an analytical study
Tiwari et al
View accepted manuscript
, Bias voltage-tunable existence boundaries of phononic frequency combs in nonlinear mechanical resonators based on 2D materials - an analytical study
PDF
, Bias voltage-tunable existence boundaries of phononic frequency combs in nonlinear mechanical resonators based on 2D materials - an analytical study
Phononic frequency combs enable the extension of frequency-comb concepts to the domain of mechanical vibrations through nonlinear modal interactions. Here, we explore the possibility of active control of the existence boundaries of phononic frequency combs via DC bias voltage. The bias-induced modification of modal frequencies and nonlinear coupling of an electrostatically actuated MoS2 resonator modulate the energy exchange pathways that enable comb formation, thus allowing for programmable regulation of the existence boundaries.
Test and analysis methods of trace iron doped titanium dioxide
Yu et al
View accepted manuscript
, Test and analysis methods of trace iron doped titanium dioxide
PDF
, Test and analysis methods of trace iron doped titanium dioxide
This study presents a test and analysis method for trace iron-doped titanium dioxide using electron probe microanalysis, X-ray diffraction and Fourier-transform infrared spectroscopy. EPMA with a detection limit of 0.001 wt%, accurately quantified the iron concentrations in five doped samples as 0.008 wt%, 0.072 wt%, 0.073 wt%, 0.175 wt% and 0.448 wt%, confirming successful iron incorporation at trace levels. XRD analysis reveals that all samples maintain the anatase phase, with the (101) diffraction peak shifting systematically toward lower angles as the doping content increases indicating lattice expansion due to Fe3+ substitution for Ti4+. FTIR spectra exhibit characteristic Ti–O–Fe vibrational bands in the 770–569 cm−1 region, whose intensities correlate positively with iron concentration. Additionally, Ti–O stretching vibrations further corroborate the successful incorporation of iron into the TiO2 lattice. The combined application of these three techniques provides complementary evidence for both elemental quantification and structural validation, this work offers an effective analytical approach for investigating trace-doped metal oxides.
Early-stage helium behavior in U
Si
: Firstprinciples study of diatomic nucleation and vacancy-limited growth
Feng et al
View accepted manuscript
, Early-stage helium behavior in U3Si2 : Firstprinciples study of diatomic nucleation and vacancy-limited growth
PDF
, Early-stage helium behavior in U3Si2 : Firstprinciples study of diatomic nucleation and vacancy-limited growth
The behavior of helium (He) in U 3 Si 2 under irradiation directly impacts fuel swelling and mechanical integrity, crucial for accidenttolerant fuel performance. This study employs first-principles calculations to investigate He dissolution, clustering, and diffusion at the atomic scale.Results show that He favors octahedral interstitial site, with a strong tendency to form stable diatomic clusters, highlighting an early nucleation mechanism. Vacancy defects further trap He and facilitate cluster formation. However, cluster growth is ultimately limited by the free volume of the vacancy, supporting a vacancy-limited growth model. Diffusion calculations reveal moderate barriers for interstitial migration (~1 eV) but significantly higher barriers (>1.5 eV) for vacancy-mediated pathways, indicating suppressed long-range transport in defective regions.
Orbital Hall conductivity in a Kekulé distorted graphene with spin-orbit coupling
Brandão da Silva et al
View accepted manuscript
, Orbital Hall conductivity in a Kekulé distorted graphene with spin-orbit coupling
PDF
, Orbital Hall conductivity in a Kekulé distorted graphene with spin-orbit coupling
We conducted a comprehensive investigation of gapped graphene influenced by a Kekulé-O distortion in the presence of spin-orbit coupling. We analyzed the band structure and derived the intrinsic orbital-magnetic-moment operator. Next, we evaluated the orbital current density and its corresponding orbital Hall conductivity. Our results show that both the Kekulé-O distortion gap and the spin-orbit coupling terms significantly affect the orbital Hall conductivity. This work highlights the importance of these factors in shaping the electrical behavior of gapped graphene.
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The following article is
Open access
Rayleigh-Bénard thermal convection in emulsions: A short review
F. Pelusi
et al
2026
EPL
154
23001
View article
, Rayleigh-Bénard thermal convection in emulsions: A short review
PDF
, Rayleigh-Bénard thermal convection in emulsions: A short review
Thermally driven emulsions arise in a broad range of natural and industrial contexts, yet their fundamental physical understanding remains only partially established. Emulsions exhibit a complex, concentration-dependent rheology, ranging from Newtonian (dilute emulsions) to yield stress (concentrated emulsions). In buoyancy-driven flows, the complex structure and rheology of the emulsion are strongly coupled to convective flows, giving rise to fascinating and non-trivial phenomena involving stability, transient dynamics, and morphological evolution of the system. We review recent progress on thermally driven emulsions in the celebrated Rayleigh-Bénard configuration, offering new perspectives on the behaviour of soft materials in thermal convection.
The following article is
Open access
On the importance of stochasticity in closures of turbulence
A. Freitas
et al
2026
EPL
154
23002
View article
, On the importance of stochasticity in closures of turbulence
PDF
, On the importance of stochasticity in closures of turbulence
Deterministic closures for coarse-grained turbulence models help reproduce mean statistics, but often fail to capture the finite-time growth of uncertainty. Using the framework of shell models as a quantitative multi-scale testbed, we compare fully resolved simulations with large-eddy simulations using either stochastic or deterministic subgrid closures. While in the fully resolved system a single microscopic perturbation is rapidly amplified by strongly chaotic dynamics, truncation produces a strong delay and suppression of variance growth when uncertainty is introduced through initial condition perturbations only. We show that a data-driven Langevin-type stochastic closure restores the correct timing and magnitude of variance growth across scales, demonstrating that sustained stochasticity is essential for predictability in reduced turbulent dynamics.
The following article is
Open access
From quasiperiodicity to a complete coloring of the Kohmoto butterfly
Ram Band and Siegfried Beckus 2026
EPL
154
22001
View article
, From quasiperiodicity to a complete coloring of the Kohmoto butterfly
PDF
, From quasiperiodicity to a complete coloring of the Kohmoto butterfly
The spectra of the Kohmoto model give rise to a fractal phase diagram, known as the Kohmoto butterfly. The butterfly encapsulates the spectra of all periodic Kohmoto Hamiltonians, whose index invariants are sought after. Topological methods are ill defined due to the discontinuous periodic potentials, and hence fail to provide index invariants. This letter overcomes that obstacle and provides a complete classification of the Kohmoto model indices —suggesting new physical invariants instead of Chern indices. Our approach encodes the Kohmoto butterfly as a spectral tree graph, reflecting the quasiperiodic nature via the periodic spectra. This yields a complete coloring of the phase diagram and a new perspective on other spectral butterflies.
The following article is
Open access
Einstein's equations in electromagnetic media
Eren Erberk Erkul and Ulf Leonhardt 2026
EPL
154
16003
View article
, Einstein's equations in electromagnetic media
PDF
, Einstein's equations in electromagnetic media
In this paper, we extend Plebanski's mapping to encode the Einstein equations in Arnowitt-Deser-Misner (ADM) form within a bianisotropic electromagnetic medium. We realise this by translating the ADM constraints and evolution equations into dynamical conditions on the medium's constitutive parameters. These transformed equations are then linearised in vacuum to derive gravitational-wave analogues as perturbations of the optical medium.
The following article is
Open access
Erratum: Trimaximal mixing and extended magic symmetry in a model of neutrino mass matrix
Labh Singh
et al
2026
EPL
154
19901
View article
, Erratum: Trimaximal mixing and extended magic symmetry in a model of neutrino mass matrix
PDF
, Erratum: Trimaximal mixing and extended magic symmetry in a model of neutrino mass matrix
Original article:
EPL
142
(2023) 64002
The following article is
Open access
Towards twisted, topological, and quantum graphene plasmonics
A. O. Soares and Nuno M. R. Peres 2026
EPL
View article
, Towards twisted, topological, and quantum graphene plasmonics
PDF
, Towards twisted, topological, and quantum graphene plasmonics
In this article, we analyze the quantum and topological properties of graphene-based plasmonic systems. We consider the following plasmonic materials: single-layer graphene, twisted bilayer graphene, and other graphene stackings, as well as the following architectures: graphenebased gratings, grids, chains of graphene disks, and the kagomé lattice.
The following article is
Open access
Generalized wave-particle-entanglement triality
Ziheng Ding
et al
2026
EPL
View article
, Generalized wave-particle-entanglement triality
PDF
, Generalized wave-particle-entanglement triality
Photon's dual nature, manifesting as both wave-like and particle-like behavior, is a phenomenon known as wave-particle duality and remains one of the most perplexing mysteries in quantum mechanics. In this work, we explore the relationships among the wave behavior, particle behavior, and entanglement of quantum states. We show the strong complementary relationships for bipartite isolated systems in terms of the generalized quantum entropic measures. This provides a measureindependent result going beyond all the existed complementary results based on specific measures. We further extend the results for non-isolated systems.
The following article is
Open access
Optimal preparation of the
state for qubits with XY coupling
Dalton Jones and Armin Rahmani 2026
EPL
View article
, Optimal preparation of the W state for qubits with XY coupling
PDF
, Optimal preparation of the W state for qubits with XY coupling
Using simulated annealing, we find optimal protocols that evolve a simple product state into a three-qubit $W$ state with a Hamiltonian that describes XY coupling and single-qubit gates, and determine the associated quantum speed limit. Applying Pontryagin’s minimum principle, we fully characterize the optimal “bang-bang” protocols. While leakage affects performance, the protocols remain robust to implementation errors and operate well within relaxation and decoherence times. Our findings highlight Pontryagin’s principle as a powerful tool for designing pulse shapes that directly link device interactions to specific quantum gates and target states.
The following article is
Open access
A geometric extension of quantum mechanics based on an energy-time ambiguity in the Schrödinger Picture
Tomer Shushi 2026
EPL
View article
, A geometric extension of quantum mechanics based on an energy-time ambiguity in the Schrödinger Picture
PDF
, A geometric extension of quantum mechanics based on an energy-time ambiguity in the Schrödinger Picture
In this short paper, we show that, within the Schrödinger picture, quantum mechanics exhibits a fundamental ambiguity in the roles of energy and time, opening the possibility that neither should be regarded as ontologically primitive. Motivated by this ambiguity, we propose a geometric reformulation in which the total curvature of a surface bulk generates quantum evolution. We show that all physically detectable quantum transformations are encoded in the boundary geometry, so that the effective structure acquires a holographic character. We further consider the model from a relational perspective, examine special cases, and discuss qualitative and quantitative connections with the role of geometry in general relativity.
The following article is
Open access
Three-dimensional contractile droplet under confinement
A. Tiribocchi
et al
2026
EPL
154
17001
View article
, Three-dimensional contractile droplet under confinement
PDF
, Three-dimensional contractile droplet under confinement
We numerically study the dynamics of a three-dimensional contractile fluid droplet in the bulk and under confinement. We show that varying activity leads to a variety of shapes and motile regimes whose motion is driven by an interplay between spontaneous flows and elasticity. In the bulk the droplet self-propels unidirectionally, acquiring either an almost spherical shape at intermediate activity or a peanut-like geometry for larger values. Under confinement, the droplet exhibits a previously unreported oscillating dynamics characterized by periodic hits against opposite walls of a microchannel while moving forward. These results could be of interest for the study of artificial microswimmers and their biological analogs, such as living cells.
More Open Access articles
Maximal work extraction from finite quantum systems
A. E. Allahverdyan
et al
2004
EPL
67
565
View article
, Maximal work extraction from finite quantum systems
PDF
, Maximal work extraction from finite quantum systems
Thermodynamics teaches that if a system initially off-equilibrium
is coupled to work sources, the maximum work that it may yield is
governed by its energy and entropy. For finite systems this bound
is usually not reachable. The maximum extractable work compatible
with quantum mechanics (“ergotropy”) is derived and expressed
in terms of the density matrix and the Hamiltonian. It is related
to the property of majorization: more major states can provide
more work. Scenarios of work extraction that contrast the
thermodynamic intuition are discussed,
e.g.
a state
with larger entropy than another may produce more work, while
correlations may increase or reduce the ergotropy.
Reward and cooperation in the spatial public goods game
A. Szolnoki and M. Perc 2010
EPL
92
38003
View article
, Reward and cooperation in the spatial public goods game
PDF
, Reward and cooperation in the spatial public goods game
The promise of punishment and reward in promoting public cooperation is debatable. While punishment is traditionally considered more successful than reward, the fact that the cost of punishment frequently fails to offset gains from enhanced cooperation has lead some to reconsider reward as the main catalyst behind collaborative efforts. Here we elaborate on the “stick
vs.
carrot” dilemma by studying the evolution of cooperation in the spatial public goods game, where besides the traditional cooperators and defectors, rewarding cooperators supplement the array of possible strategies. The latter are willing to reward cooperative actions at a personal cost, thus effectively downgrading pure cooperators to second-order free-riders due to their unwillingness to bear these additional costs. Consequently, we find that defection remains viable, especially if the rewarding is costly. Rewards, however, can promote cooperation, especially if the synergetic effects of cooperation are low. Surprisingly, moderate rewards may promote cooperation better than high rewards, which is due to the spontaneous emergence of cyclic dominance between the three strategies.
Orbitronics: Orbital currents in solids
Dongwook Go
et al
2021
EPL
135
37001
View article
, Orbitronics: Orbital currents in solids
PDF
, Orbitronics: Orbital currents in solids
In solids, electronic Bloch states are formed by atomic orbitals. While it is natural to expect that orbital composition and information about Bloch states can be manipulated and transported, in analogy to the spin degree of freedom extensively studied in past decades, it has been assumed that orbital quenching by the crystal field prevents significant dynamics of orbital degrees of freedom. However, recent studies reveal that an orbital current, given by the flow of electrons with a finite orbital angular momentum, can be electrically generated and transported in wide classes of materials despite the effect of orbital quenching in the ground state. Orbital currents also play a fundamental role in the mechanisms of other transport phenomena such as spin Hall effect and valley Hall effect. Most importantly, it has been proposed that orbital currents can be used to induce magnetization dynamics, which is one of the most pivotal and explored aspects of magnetism. Here, we give an overview of recent progress and the current status of research on orbital currents. We review proposed physical mechanisms for generating orbital currents and discuss candidate materials where orbital currents are manifest. We review recent experiments on orbital current generation and transport and discuss various experimental methods to quantify this elusive object at the heart of
orbitronics
—an area which exploits the orbital degree of freedom as an information carrier in solid-state devices.
Dynamics of Dzyaloshinskii domain walls in ultrathin magnetic films
André Thiaville
et al
2012
EPL
100
57002
View article
, Dynamics of Dzyaloshinskii domain walls in ultrathin magnetic films
PDF
, Dynamics of Dzyaloshinskii domain walls in ultrathin magnetic films
We explore a new type of domain wall structure in ultrathin films with perpendicular anisotropy, that is influenced by the Dzyaloshinskii-Moriya interaction due to the adjacent layers. This study is performed by numerical and analytical micromagnetics. We show that these walls can behave like Néel walls with very high stability, moving in stationary conditions at large velocities under large fields. We discuss the relevance of such walls, that we propose to call Dzyaloshinskii domain walls, for current-driven domain wall motion under the spin Hall effect.
Spin-orbit–induced spin splittings in polar transition metal dichalcogenide monolayers
Y. C. Cheng
et al
2013
EPL
102
57001
View article
, Spin-orbit–induced spin splittings in polar transition metal dichalcogenide monolayers
PDF
, Spin-orbit–induced spin splittings in polar transition metal dichalcogenide monolayers
The Rashba effect in quasi two-dimensional materials, such as noble metal surfaces and semiconductor heterostructures, has been investigated extensively, while interest in real two-dimensional systems has just emerged with the discovery of graphene. We present
ab initio
electronic structure, phonon, and molecular-dynamics calculations to study the structural stability and spin-orbit–induced spin splitting in the transition metal dichalcogenide monolayers MXY (M = Mo, W and X, Y = S, Se, Te). In contrast to the non-polar systems with X = Y, in the polar systems with X ≠ Y the Rashba splitting at the Γ-point for the uppermost valence band is caused by the broken mirror symmetry. An enhancement of the splitting can be achieved by increasing the spin-orbit coupling and/or the potential gradient.
Non-collinear antiferromagnets and the anomalous Hall effect
J. Kübler and C. Felser 2014
EPL
108
67001
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, Non-collinear antiferromagnets and the anomalous Hall effect
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, Non-collinear antiferromagnets and the anomalous Hall effect
The anomalous Hall effect is investigated theoretically by employing density functional calculations for the non-collinear antiferromagnetic order of the hexagonal compounds Mn
Ge and Mn
Sn using various planar triangular magnetic configurations as well as unexpected non-planar configurations. The former give rise to anomalous Hall conductivities (AHC) that are found to be extremely anisotropic. For the planar cases the AHC is connected with Weyl points in the energy-band structure. If this case were observable in Mn
Ge, a large AHC of about
should be expected. However, in Mn
Ge it is the non-planar configuration that is energetically favored, in which case it gives rise to an AHC of
. The non-planar configuration allows a quantitative evaluation of the topological Hall effect that is seen to determine this value of
to a large extent. For Mn
Sn it is the planar configurations that are predicted to be observable. In this case the AHC can be as large as
Nuclear laser spectroscopy of the 3.5 eV transition in Th-229
E. Peik and Chr. Tamm 2003
EPL
61
181
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, Nuclear laser spectroscopy of the 3.5 eV transition in Th-229
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, Nuclear laser spectroscopy of the 3.5 eV transition in Th-229
We propose high-resolution laser spectroscopy of the 3.5 eV
nuclear transition in Th-229 in isolated atoms. Laser
excitation of the nucleus can be detected efficiently in a
double-resonance method by probing the hyperfine structure of a
transition in the electron shell. It is shown that for a suitably
chosen electronic level, the frequency of the nuclear transition
is independent of external magnetic fields to first order and of
electric fields to second order. This makes Th-229 a
possible reference for an optical clock of very high accuracy.
The nuclear-electronic double-resonance method can be
conveniently applied to a laser-cooled ion of
229
Th
3+
in a radiofrequency trap. Further
applications of nuclear laser spectroscopy are discussed.
Role of the surface effect on the structural, electronic and mechanical properties of the carbide MXenes
Xian-Hu Zha
et al
2015
EPL
111
26007
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, Role of the surface effect on the structural, electronic and mechanical properties of the carbide MXenes
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, Role of the surface effect on the structural, electronic and mechanical properties of the carbide MXenes
The two-dimensional material MXene has recently attracted interest for its excellent performance in diverse perspectives. Etched from the parental MAX phase with hydrofluoric acid, the synthesized MXene surface is normally functionalized by oxygen (-O), fluorine (-F) or hydroxyl (-OH) groups. Herein, using first-principles density functional calculations, we investigate the structural, mechanical and electronic properties of the carbide MXene M
CT
(M=Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W; T=-O, -F, -OH). Both the M atom and the surface group T have a significant effect on the MXenes properties. Generally, oxygen functionalized MXenes present smaller lattice parameters and stronger mechanical strength compared to those functionalized by fluorine and hydroxyl groups.
exhibits the smallest interlayer thickness and
shows the strongest mechanical strength. In regard to electronic properties, five oxygen functionalized members M
CO
(M=Sc, Ti, Zr, Hf, W), two fluorine functionalized members M
CF
(M=Sc, Mo), and hydroxyl functionalized Sc
C(OH)
present semiconducting characteristics, but only Sc
C(OH)
exhibits a direct band gap.
Slippery pre-suffused surfaces
A. Lafuma and D. Quéré 2011
EPL
96
56001
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, Slippery pre-suffused surfaces
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, Slippery pre-suffused surfaces
We describe the slippery behaviour of textured solids filled with oil, on which other liquids are found to slip and be removed easily. We describe the criteria for achieving this slippery behaviour, and illustrate the concept by two examples, namely the lotus effect (removal of dust by mobile drops) and the coffee stain effect.
Discrete-time Markov chain approach to contact-based disease spreading in complex networks
S. Gómez
et al
2010
EPL
89
38009
View article
, Discrete-time Markov chain approach to contact-based disease spreading in complex networks
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, Discrete-time Markov chain approach to contact-based disease spreading in complex networks
Many epidemic processes in networks spread by stochastic contacts among their connected vertices. There are two limiting cases widely analyzed in the physics literature, the so-called contact process (CP) where the contagion is expanded at a certain rate from an infected vertex to one neighbor at a time, and the reactive process (RP) in which an infected individual effectively contacts all its neighbors to expand the epidemics. However, a more realistic scenario is obtained from the interpolation between these two cases, considering a certain number of stochastic contacts per unit time. Here we propose a discrete-time formulation of the problem of contact-based epidemic spreading. We resolve a family of models, parameterized by the number of stochastic contact trials per unit time, that range from the CP to the RP. In contrast to the common heterogeneous mean-field approach, we focus on the probability of infection of individual nodes. Using this formulation, we can construct the whole phase diagram of the different infection models and determine their critical properties.
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1986-present
Europhysics Letters
Online ISSN: 1286-4854
Print ISSN: 0295-5075