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Ting Min Liu, Lin Yi Zhou,
Published: 12 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2f0e

Abstract:
We study the anomalous Josephson effect induced by magnetic misorientation of asymmetric s-wave superconductor (SC)/ferromagnet insulator (FI)/normal layer/FI/d-wave SC junctions on a surface of topological insulator (TI). For the out-of-plane case, the magnetic misorientation not only leads to anomalous Josephson effects, but also realizes 0 - π state transitions. However, for the in-plane, the 0 - π state transitions do not turn up any more. In particular, the platform phenomenon for dx2-y2 -wave SC junction emerges all the time. In addition, in the context of the in-plane, the supercurrent rectification can be modulated by the magnetic misorientation. These unique phenomena can be employed to identify different d-wave superconductivities of three-dimensional TI and manufacture the supercurrent devices with such functions as phase storing, rectification, and quantum computation.
Published: 11 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2ea2

Abstract:
Experimental tests of Lorentz violation are important to our understanding of fundamental physics, and interest in them has picked up a great deal in the twenty-first century. For some of the most natural forms of Lorentz violation involving electrons and positrons, there are competing bounds coming from high-energy astrophysical observations and laboratory tests with optical atomic clocks. I discuss the advantages and limitations of both these approaches and how they may evolve in the future.
, Ying Chen, Huanyang Chen
Published: 8 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2e2a

Abstract:
Beam steering in photonic crystals is significant in manipulating light beams. In this paper, we design self-collimation, beam splitting, and negative refraction effects in photonic crystals based on metallic pairs immersed in dielectric background. By using a single array of metallic pairs, a broadband and wide-angle self-collimation effect is achieved. Meanwhile, due to the extreme anisotropy, a beam splitting effect is achieved by utilizing the kissing of equi-frequency contours. We then restructure the unit cell with glide symmetry to achieve negative refraction effect in a wide frequency range and realize the effect of flat lens. To illustrate this phenomenon, a flat lens based on the restructured unit cell is designed and numerically demonstrated.
, David McComas
Published: 8 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2e2c

Abstract:
We generalize Planck's law for black-bodies, classically described by Maxwell-Boltzmann distributions, to include space and astrophysical plasmas described by kappa distributions. This provides the spectral intensity of electromagnetic radiation emitted by black-bodies in thermal equilibrium with the surrounding and interacting plasmas. According to the generalized concept of thermal equilibrium, systems with correlations among their particles' velocities/energies, reside in stationary states described by kappa distributions associated with the thermodynamic parameters of temperature and kappa index. Using these distributions, we derive the generalized expressions of the (i) mean energy of photon ensemble, (ii) spectral intensity with respect to frequency and wavelength, and (iii) Stefan-Boltzmann law, characterized by the well-known fourth power of temperature, but now multiplied by a new kappa-dependent factor. Finally, we discuss the implications of these new developments for space and astrophysical plasmas.
Ganesh Adhikary, Tanusree Saha, Primoz Rebernik Ribic, Matija Stupar, Barbara Ressel, Jurij Urbancic, Giovanni De Ninno, A. Thamizhavel,
Published: 7 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2dc0

Abstract:
Quantum materials display exotic behaviours related to the interplay between temperature-driven phase transitions. Here, we study the electron dynamics in one such material, CaFe$_2$As$_2$, a parent Fe-based superconductor, employing time and angle-resolved photoemission spectroscopy. CaFe$_2$As$_2$ exhibits concomitant transition to spin density wave state and tetragonal to orthorhombic structure below 170 K. The Fermi surface of this material consists of three hole pockets ($\alpha$, $\beta$ and $\gamma$) around $\Gamma$-point and two electron pockets around $X$-point. The hole pockets have $d_{xy}$, $d_{yz}$ and $d_{zx}$ orbital symmetries. The $\beta$ band constituted by $d_{xz}$/$d_{yz}$ orbitals exhibit a gap across the magnetic phase transition. We discover that polarized pump pulses can induce excitations of electrons of a selected symmetry. More specifically, while $s$-polarized light (polarization vector perpendicular to the $xz$-plane) excites electrons corresponding to all the three hole bands, $p$-polarized light excites electrons essentially from ($\alpha$,$\beta$) bands which are responsible for magnetic order. Interestingly, within the magnetically ordered phase, the excitation due to the $p$-polarized pump pulses occur at a time scale of 50 fs, which is significantly faster than the excitation induced by $s$-polarized light ($\sim$ 200 fs). These results suggest that the relaxation of different ordered phases occurs at different time scales and this method can be used to achieve selective excitations to disentangle complexity in the study of quantum materials.
, V. V. Prasad, R. Rajesh
Published: 6 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2d54

Abstract:
Mpemba effect refers to the counterintuitive relaxation wherein a hotter system equilibrates faster than a cooler system when quenched to a cold temperature. Even though the effect has been illustrated for isotropically driven granular gases, a prototypical system far from equilibrium, its existence requires non-stationary initial states, limiting experimental realisation. In this paper, we demonstrate the existence of Mpemba effect in anisotropically driven granular gases, even when quenched from initial states that are stationary. Our theoretical predictions, based on kinetic theory, for the regular, inverse and strong Mpemba effects agree well with results of event-driven molecular dynamics simulations of hard discs.
M. Sowjanya, , S. R. Pilli, , T Alharbi, Anis Ahmad Chaudhary, D. Pamu, R. Chowdharuy, A.M. Fathy, Yassine Slimani, et al.
Published: 6 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2d55

Abstract:
In this study, a radio frequency magnetron sputtering technique was applied to deposit eminently oriented ZnO thin films on stainless steel (SS316L). The effect of different ratios (Ar:O2) of gas flow [(20:0), (15:5), (10:10), (5:15), (0:20)] on optical and structural properties of CeO2 doped ZnO thin films has been examined. The increase in grain size of thin films was observed with a partial increase in the Ar:O2 sputtering gas at substrate temperature of 673 K. The average surface roughness of the thin films has increased with sputtering gas. The photoluminescence peak exhibited a broad green–yellow band spiked at 467 nm for all the samples of CeO2 doped ZnO thin films and a wide band of visible light focused in the 500–600 nm range. Intensity reduction of deep level emission peaks of ZnO films was observed. The refractive index of undoped and CeO2 doped ZnO thin films with various sputtering gas ratios (Ar:O2) were also investigated. The optimized argon gas flow rate findings allow us to choose the deposition conditions for CeO2 doped ZnO thin films for solar thermal applications.
Published: 5 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2cfa

Abstract:
We show that in theories of gravitation based on affine geometries the torsion field, that takes a dynamical character, not only the chiral magnetic effect (CME) intervenes in the wash up of the chiral anomaly but also the chiral vortical effect (CVE) and the coupled chiral effect (CCE) coming from hypermagnetic field interaction with the primordial plasma are crucial in a realistic physical scenario, as in the case of the early universe. We also show that the equation governing the wash up takes the form n_{chiral}=((((8e²)/(16π²))(1/σ){(∇×B)⋅B+(γ₂q_{s}n_{s}H_{mix}+γ₁H_{V})|B|²})/((2Γ_{flip}+((8e²)/(16π²))((e²)/(2π²))(6/(σT²))|B|²))) supplemented with the dynamical equation for the torsion vector h_{μ} containing the helicities and other axial couplings. The role played by the neutrinos in interaction with the axion field in this theoretical framework is briefly discussed.
Xiangxian Wang, Tianxu Jia, Yaqian Ren, Yingwen Su, Zhenyu Chen, , Xiaolei Wen
Published: 5 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2cf9

Abstract:
In this study, multi-beam surface plasmon (SP) interference lithography was theoretically proposed and demonstrated to fabricate periodic two-dimensional sub-wavelength structures. The lithography structures were based on an attenuated total reflection prism used to excite the SPs using a 442 nm laser. Circular lattices with periods of 166 and 288 nm were successfully obtained via three- and six-beam SP interference lithography, respectively; these lattices exhibited an identical feature size of 96 nm. Square dot arrays with a 177 nm period and 88.5 nm spot size were obtained by four-beam SP interference lithography. The proposed lithography technology has a simple structure and is economical; further, it may provide an effective method for the fabrication of two-dimensional sub-wavelength structures.
Wending Zhang, , Xing Wang, Chen Niu, Haowei Chen, Jintao Bai
Published: 5 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2cfb

Abstract:
We report a method for optical trapping and three-dimensional manipulation of light-absorbing particles in air based on a hollow beam. The particles can be stably trapped for hours in the focused hollow beam with either horizontal or vertical trapping configuration. Particle revolution in the lateral plane (x-y plane) is achieved by employing a wedge prism to deviate and rotate the optical traps. And the particle movement along the laser propagating direction (z direction) is realized by changing the size of the hollow trapping beam. The mechanism of particle trapping and manipulation in air is analyzed based on the characteristics of photophoretic force. As high trapping power is avoided, this method is meaningful for the particles of low damage threshold and provides a useful tool for in-situ analysis of the single aerosol particle in a non-destructive and non-contact manner.
Yue Lu, Dehu Li, Yue Wang, Zhifeng Liu
Published: 4 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2c97

Abstract:
Magnetic semiconductors have become a widely concerned direction in spintronic materials due to their unique energy band structure and two different spin transport channels. In this work, we imported rare-earth atoms into quaternary Heusler compounds and based on Slater-Pauling rules. Magnetic semiconductors FeCrYSn, FeCrYGe, FeCrLuGe, FeCrLuSn, FeCrLuSi, FeVLuSb, MnCrYSb, and MnCrLuSb were found through first- principle calculations. According to the result, the band gaps of these quaternary Heusler compounds are extremely narrow.
, Changgui Gu, Chuansheng Shen, Huijie Yang
Published: 4 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2c98

Abstract:
Globally, forests are increasingly being affected by invasive alien pests, some of which have caused wholesale destruction of trees. Recent research suggests that, in the United States, large scale forests have been invaded by an astonishing number (>450) of tree-feeding pests. Invasive alien pests always induce cascading ecological effects, leading to harmful socioeconomic consequences; however, the prevention and control of invasive alien pests in forests have been facing significant challenges worldwide. Here, we studied theoretically the control of invasive nonnative pests in warm-temperate deciduous forest ecosystems by their natural enemies (biological control), and controlled them to an extent that ecosystems can bear. We obtained a novel type of spiral wave in the spatial distribution of population density, and also observed a transition phenomenon between spiral wave and anti-spiral wave, which is explained by a mathematical analysis. Specifically, the formation of this type of spiral wave is attributed to the directional transformation of states between the period-5 orbits under the impact of diffusion transport. And the transition phenomenon is caused by changes of relative positions of the period-5 orbits in phase space. Moreover, we also found a novel type of instability of spiral wave, which includes a birth-growth-death process of spiral fragments. The findings provide possible regularities in the process of biological control of invasive alien pests in the complex and changeable forest ecosystems, which may guide actual biological control projects.
Joydeep Chakrabortty, , Shakeel Ur Rahaman, Michael Spannowsky
Published: 4 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2c96

Abstract:
At energies below the electroweak scale, baryon number $B$ and lepton number $L$ violating processes are of significant importance in identifying the nature of UV extensions of the Standard Model. The imprint of UV theories on low-energy measurements can be calculated to a high accuracy using the theoretical framework of the Low Energy Effective Theory (LEFT). Using $B,\;L$ and the operators' dimensions as classifying characteristics, we construct a network connecting operator classes of the LEFT with the Standard Model Effective Theory (SMEFT). Following the links of this network, the contact interactions described by the effective operators of LEFT can be unambiguously embedded into those of SMEFT, which enables us to constrain the possible realisations of UV theories. In turn, this can help to prioritize low energy measurements with the aim of comprehensively testing all classes of LEFT and SMEFT operators.
, , Magnus Olof Borgh
Published: 1 October 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2c53

Abstract:
We study the relaxation dynamics of quantum turbulence in a two-component Bose-Einstein condensate containing half-quantum vortices. We find a temporal scaling regime for the number of vortices and the correlation lengths that at early times is strongly dependent on the relative strength of the inter-species interaction. At later times we find that the scaling becomes universal, independent of the inter-species interaction, and approaches that numerically observed in a scalar Bose-Einstein condensate.
Shengli Ma, Jing Zhang, Xin-Ke Li, Ya-Long Ren, Ji-Kun Xie, Ming-Tao Cao, Fu-Li Li
Published: 29 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2b5c

Abstract:
We propose an experimentally feasible scheme for the dissipative generation of stable entanglement of superconducting qubits via coupling modulation without applying any drives on qubits and resonator. Firstly, we study the circuit of one superconducting transmission line resonator coupled to two separated qubits via two superconducting quantum interference devices (SUQIDs). By modulating the inductance of the SQUIDs via external fluxes, we can tailor an appropriate qubit-resonator couplings with both red- and blue-sideband interactions. Combined with the photon loss of the resonator, the two qubits can be autonomously steered into a long-lived entangled state with high-fidelity. Moreover, we extend the model to one resonator coupled to two separated qubit chains, each of which contains $N$ linearly coupled superconducting qubits. We show that the lossy resonator can drive the whole system into a unique dark state, i.e., a series of $N$ entangled pairs of qubits across the chains can be stabilized at the stationary state. So, the present work enables the preparation of stable long-range entangled state between the two qubits in the end sites of the chains, which plays important role for implementing scalable quantum computation and quantum communication.
Cynthia J. Reichhardt, Charles Reichhardt
Published: 29 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2adc

Abstract:
Odd viscosity arises in systems with time reversal symmetry breaking, which creates non-dissipative effects. One method to probe changes in viscosity is to examine the dynamics of a single probe particle driven though a medium, a technique known as active rheology. We show that active rheology in a system with odd viscosity and no quenched disorder reveals a variety of novel effects, including a speed up of the probe particle with increasing system density when the background medium creates a velocity boost of the driven particle due to the Magnus effect. In contrast, the probe particle velocity in the dissipation-dominated limit monotonically decreases with increasing system density. We also show that the odd viscosity imparts a Hall angle to the probe particle, and that both the Hall angle and the velocity boost depend strongly on the drive. These results should be general to other systems with odd viscosity, including skyrmions in chiral magnets.
Jiu Hui Wu, Lin Zhang, Jiang Ke Zhou
Published: 29 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2b5b

Abstract:
Considering that the catastrophe theory could describe quantitatively any phase transition process, we adopt the folding and cusp catastrophe types as the potential function in the Schrödinger equation to attempt to link the quantum dynamics and the classical wave motions, respectively. Thus, through the dimensionless analysis a novel kind of partial differential equations is derived out. When the scaling parameter of the novel equation is equal to the Plank's constant, this equation becomes a detailed time-independent Schrödinger equation, from which Bohr correspondence principle can be found. On the other hand, when the scaling parameter tends to zero, this equation could degenerate to the classical Helmholtz equation. Therefore, this novel kind of equations could describe quantitatively the variation process of the wave functions from the macroscopic level to the quantum size.
Kangjia Wang, Pei-Ling Zhang
Published: 27 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2a62

Abstract:
In this manuscript, the time-space fractional Sasa-Satsuma equation is considered. A novel and interesting method called as He's frequency formulation, which is derived from the ancient Chinese algorithm(ACG)-Ying Bu Zu Shu (盈不足术), is employed to construct its periodic solution. This ancient algorithm originated from an ancient Chinese mathematics monograph-The Nine Chapters on the Mathematical Art (九章算术) compiled in the Han Dynasty(后汉) about second century AD. As anticipated, the obtained solution is consistent with that of the variational method. It strongly verifies the effectiveness and reliability of the proposed method. Finally, the performances of the solution with different fractional orders are presented through the 2-D and 3-D surfaces. The discovery of this work is expected to contribute to the study of periodic solutions in physics.
Yao Shen, Chi-Chun Zhou, Wu-Sheng Dai, Mi Xie
Published: 24 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac29f1

Abstract:
The exact solution of the interacting many-body system is important and is difficult to solve. In this paper, we introduce a group method to solve the interacting many-body problem using the relation between the permutation group and the unitary group. We prove a group theorem first, then using the theorem, we represent the Hamiltonian of the interacting many-body system by the Casimir operators of unitary group. The eigenvalues of Casimir operators could give the exact values of energy and thus solve those problems exactly. This method maps the interacting many-body system onto an intermediate statistical representation. We give the relation between the conjugacy-class operator of permutation group and the Casimir operator of unitary group in the intermediate statistical representation, called the Gentile representation. Bose and Fermi cases are two limitations of the Gentile representation. We also discuss the representation space of symmetric and unitary group in the Gentile representation and give an example of the Heisenberg model to demonstrate this method. It is shown that this method is effective to solve interacting many-body problems.
Published: 24 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac29f0

Abstract:
Einstein observers in flat space-time are inertial observers which use light to synchronize their clocks. For such observers, speed of light is a constant by construction. However, one can use super-translations to change coordinates from Einstein to BMS coordinates. From the point of view of BMS observers, speed of light is not a constant all over the space-time and in all directions. So in general, clocks which are synchronized for Einstein observers are not synchronized for BMS observers, and vice versa. Based on this fact, we propose a local observable for detecting the soft hairs, which is the variations in speed of light for such observers. We also investigate the relation of this observable to gravitational memory, which is a permanent change of position of test particles at infinity, after a gravitational wave passes completely from them. It is shown that the BMS time coordinate is the physical time after a gravitational wave, and it is the legitimate time to be used to calculate the light speed. Based on this argument, the analysis predicts a permanent change in the speed of light rays which propagate in asymptotics after a gravitational wave. Moreover, it is explained how this change is related to the gravitational memory by comparing their significance in observations.
Published: 22 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac293d

Abstract:
We explore the hypothesis of magnetic monopoles and propose a magnetic field configuration that yields a Coulomb-type potential in the electric quadrupole moment system. This field configuration establishes a forbidden region for the neutral particle, hence, it establishes a cut-off point. We thus analyse the influence of this cut-off point on a Coulomb-type potential by searching for bound state solutions to the Schr\"odinger equation.
Avanish Kumar, , Murari Singh
Published: 17 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac27e6

Abstract:
A careful examination of the Quasi-Localized Modes (QLM) that exist in a generic atomistic model of a glass former reveals at least two types of them, each exhibiting a different density of states, one depending on the frequency as $\omega^3$ and the other as $\omega^4$. The properties of the glassy energy landscape that is responsible for the two types of modes is examined here, explaining the analytic feature responsible for the creations of (at least) two families of QLM's. It is argued that the QLM's that are revealed by diagonalizing the Hessian matrix are not related to possibly existing Two-Level Systems (TLS).
Nick James, , Howard Bondell
Published: 16 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2752

Abstract:
This paper introduces a novel approach to spatio-temporal data analysis using metric geometry to study the propagation of COVID-19 across the United States. Using a geodesic Wasserstein metric, we analyse discrepancies between the density functions of new case counts on any given day, incorporating the geographic spread of cases. First, we apply this to identify the periods during which the changes in the geographic distribution of COVID-19 were most profound. The greatest shift occurred between May and June of 2020, when COVID-19 shifted from mostly dominating the Northeastern states to a wider distribution across the country. We support our findings with a new measure of the extent of geodesic variance of a distribution, demonstrating that the geographic imprint of COVID-19 was most concentrated in May 2020. Next, we investigate whether the epidemic exhibited meaningful patterns of spatial reversion, where similar geographic distributions return later. We identify broad similarity between the spread of COVID-19 across the US between the second and third waves, and to a lesser extent, the reemergence of the first wave's Northeastern dominance closer to the present day. This methodology could provide new insights for analysts to monitor the dynamical spread of epidemics and enable regional policymakers to protect their localities. More broadly, the framework we introduce could be applied to a variety of problems evolving over space and time.
Guillaume Ricard,
Published: 16 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2751

Abstract:
Wave turbulence in quasi-1D geometry is usually not investigated experimentally since low-order resonant wave interactions are theoretically prohibited. Here, we report on the first observation of unidirectional capillary-wave turbulence on the surface of a fluid in a canal. We also show that five-wave interactions are the lowest-order resonant process subsisting at small scales, and are thus probably the one generating such quasi-1D capillary wave turbulence. We show that the wave spectrum is compatible with the corresponding dimensional analysis prediction. The main assumptions of weak turbulence theory are also verified experimentally. Quasi-1D wave turbulence could be thus highlighted in other fields of wave turbulence.
Published: 13 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2654

Abstract:
We relate the anomaly in the noise color of spin ice to the emergent nature of its magnetic monopoles and their random walk. Monopoles are quasi-particles, and the spin vacuum in which they wander is not structureless. Rather, the underlying spin ensemble filters the thermal white noise, leading to non-trivial coevolution. Thus, monopoles can be considered as "dressed" random walkers, activated by a non-trivial stochastic noise that subsumes mutual interactions and the coevolution of their spin vacuum. From this, we suggest that recent experimental results are interpretable in terms of monopole subdiffusion. We then conjecture relations between the color of the noise and other observables, such as relaxation time, monopole density, the dynamic exponent, and the order of the annihilation reaction, which suggests to us the introduction of spin-ice-specific critical exponents in a neighborhood of the ice manifold criticality.
Published: 13 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2655

Abstract:
Dry sliding friction is a complex but ubiquitous phenomenon. Experimental studies of friction produce large amounts of data, while most models are phenomenological rather than deduced from fundamental principles. Proper identification of relevant degrees of freedom is crucial for the development of adequate frictional models, such as the state-and-rate models. Topological data analysis is a mathematical method for the dimensionality reduction for datasets characterizing surface roughness, contact of rough surfaces and frictional sliding. We study tribological systems including the surface roughness and multiasperity contacts using 3×3, 4×4, and 5×5 pixel patches. Depending on whether the surface is isotropic or anisotropic with particular lay directions, the data tends to concentrate at certain "primary" and "secondary" circles yielding different values of the Betti numbers. Scale dependency of corresponding structures is analyzed with persistence diagrams. Moreover, statistics of stick-slip zones can provide insights on relevant internal degrees of friction.
Liming Zhao, Yun-Song Zhou, Gong-Min Wei
Published: 13 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2652

Abstract:
The finding of Photon Hall effect (PHE) on metal surface is an important progress in photonics, but it will be more practical if PHE can be realized in line-type waveguide. In this paper, we suggested a way to realize PHE in two-dimensional photonic crystal (PC) waveguide. Numerical simulation results show that the propagating direction and strength of light in the PC waveguide can be controlled by the polarization state of incident light. Different from the PHE on metal surface, the PHE in PC waveguide can be driven not only by circularly polarized light, but also by linearly polarized light. The PHE in PC waveguide can be attributed to the interference of the two component waves excited by the incident light.
, Alfred Z Msezane, Stanislav Artamonov, George Japaridze, Yuliya Leevik
Published: 13 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2651

, Pierre Le Doussal
Published: 10 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac25a9

Abstract:
We obtain a simple formula for the stationary measure of the height field evolving according to the Kardar-Parisi-Zhang equation on the interval [0, L] with general Neumann type boundary conditions and any interval size. This is achieved using the recent results of Corwin and Knizel (arXiv:2103.12253) together with Liouville quantum mechanics. Our formula allows to easily determine the stationary measure in various limits: KPZ fixed point on an interval, half-line KPZ equation, KPZ fixed point on a half-line, as well as the Edwards-Wilkinson equation on an interval.
, A. K. Rao
Published: 10 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac25a8

Abstract:
We demonstrate that the standard St{$\ddot u$}ckelberg-modified Proca theory (i.e. a massive Abelian 1-form theory) respects the classical gauge and corresponding quantum (anti-)BRST symmetry transformations in any arbitrary dimension of spacetime within the framework of Becchi-Rouet-Stora-Tyutin (BRST) formalism. We further show that the St{$\ddot u$}ckelberg formalism gets modified in the two (1+1)-dimensions of spacetime due to a couple of discrete duality symmetry transformations in the theory which turn out to be responsible for the existence of the nilpotent (anti-)co-BRST symmetry transformations corresponding to the nilpotent (anti-)BRST symmetry transformations of our theory. These nilpotent symmetries exist together in the modified version of the two (1+1)-dimensional (2D) Proca theory. We provide the mathematical basis for the modification of the St{$\ddot u$}ckelberg-technique, the existence of the discrete duality as well as the continuous (anti-)co-BRST symmetry transformations in the 2D modified version of Proca theory.
Shi-Hai Dong, Wen-Hua Huang, Won Sang Chung, Parisa Sedaghatnia, Hassan Hassanabadi
Published: 7 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2453

Gangyi Zhu, Feifei Qin, Ru Wang, Xiaoxuan Wang, Junfeng Lu, Ying Yang, Chunxiang Xu, Yongjin Wang
Published: 7 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2456

Mohd Alam, Arkadeb Pal, Khyati Anand, Surajit Ghosh, Saurabh Tripathi, Ranjan Kumar Singh, Anup K. Ghosh, H. D. Yang, Sandip Chatterjee
Published: 7 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2455

Chunfeng Cai, Boxuan Zhang, Xiaoyu Wang, Li Ling, Tianning Xu, Tianhao Huang, He Zhu, Gang Bi, Huizhen Wu
Published: 7 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2454

, Hugo Fort
Published: 7 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2457

Abstract:
In evolutionary game theory, pair interactions are usually defined through so-called payoff matrices, which can be decomposed as linear combinations of basis matrices that represent just four different orthogonal interaction types. In this paper, we take the first steps in exploring the utility of this decomposition in ecology. We introduce the componental cosines of the irrelevant, external, coordination, and conflict components of matrices to measure the relative weight of the different interaction types, and use them to analyse the composition of 33 experimentally obtained interspecific interaction matrices compiled from the literature, which reveals statistically significant correlations both between different components and some components and community productivity and biodiversity.
Xin Liang, Hongyan Lv, Jianguo Si, Yuanting Hong, Wenjian Lu, Yuping Sun
Published: 6 September 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac23eb

, Didier Sornette
Published: 31 August 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac225d

Abstract:
We study tensorial elastic wave transport in two-dimensional densely fractured media using numerical simulations and document transitions from propagation to diffusion and to localisation/delocalisation. For large fracture stiffness, waves are propagative at the scale of the system. For small stiffness, multiple scattering prevails, such that waves are diffusive in disconnected fracture networks, and localised in connected ones with a strong multifractality of the intensity field. A reentrant delocalisation is found in well-connected fracture networks due to energy leakage via evanescent waves and cascades of mode conversion.
Dominik Szczesniak, Ewa Anna Drzazga-Szczesniak
Published: 30 August 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2248

Abstract:
In the present study, we investigate impact of the non-adiabatic effects on the superconducting state in the electron-doped graphene. In particular, by using the Eliashberg formalism we analyze case scenario of the nitrogen-doped graphene, showing that the non-adiabatic effects complement electron-electron interaction and notably reduce (up to ∽40 %) pivotal thermodynamic properties, such as: the critical temperature, the superconducting gap and their characteristic ratio. Interestingly, the influence of the non-adiabatic effects is found to rise together with the increase of the depairing Coulomb interaction. These observations are elucidated based on the structure of the vertex corrections to the electron-phonon interaction. As a result, we draw direction for the future research in the field of the two-dimensional non-adiabatic superconductivity.
Fenglin Deng, Peiheng Jiang, Yi Lu,
Published: 24 August 2021
EPL (Europhysics Letters); https://doi.org/10.1209/0295-5075/ac2073

Abstract:
Sr-doped infinite layer nickelate Nd1-xSrxNiO2 was recently reported as a superconductor analogous to the layered copper oxides. Previous works revealed that two bands of mainly Nd 5d and Ni 3d characters cross the Fermi level in NdNiO2, whose behaviors under Sr doping are still unclear. We perform density functional theory calculations of supercell Nd1-xSrxNiO2 to systematically study the evolution of its electronic structure at different doping levels. Our results show that a relative shift occurs between the Nd 5d and Ni 3d bands with Sr doping, deviating significantly from the commonly adopted rigid-band approximation for studying doped compounds. In addition, the O-p bands rise with respect to Fermi level when Sr concentration increases, resulting in a reduced charge transfer gap. We further estimate the hole concentrations on each band and Hall coefficients, and discuss their relevance to recent experiments.
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