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Perfect cycles in the synchronous Heider dynamics in complete network

Physical Review E 2022年第5期105卷 054312-054312页

作者： Zdzislaw Burda Malgorzata J. Krawczyk Krzysztof Kułakowski AGH University of Science and Technology Faculty of Physics and Applied Computer Science al. Mickiewicza 30 30-059 Kraków Poland

We discuss a cellular automaton simulating the process of reaching Heider balance in a fully connected network. The dynamics of the automaton is defined by a deterministic, synchronous, and global update rule. The dynamics has a very rich spectrum of attractors including fixed points and limit cycles, the length and number of which change with the size of the system. In this paper we concentrate on a class of limit cycles that preserve energy spectrum of the consecutive states. We call such limit cycles perfect. Consecutive states in a perfect cycle are separated from each other by the same Hamming distance. Also the Hamming distance between any two states separated by k steps in a perfect cycle is the same for all such pairs of states. The states of a perfect cycle form a very symmetric trajectory in the configuration space. We argue that the symmetry of the trajectories is rooted in the permutation symmetry of vertices of the network and a local symmetry of a certain energy function measuring the level of balance and frustration of triads.

关键词： Dynamics of networks

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Exciton localization on p−i−n junctions in two-dimensional crystals

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Physical Review B 2022年第8期106卷 085305-085305页

作者： Bartłomiej Szafran AGH University of Science and Technology Faculty of Physics and Applied Computer Science al. Mickiewicza 30 30-059 Kraków Poland

We consider a neutral exciton localized on a model p−i−n junction defined in a two-dimensional crystal, MoSe2 and phosphorene, using a variational approach to the effective mass Hamiltonian. The variational solution to the problem with nonseparable center of mass provides the exciton density in the real space and accounts for the kinetic energy due to the exciton localization. For low values of the potential step across the junction, the exciton occupies an area which is much larger than the nominal width of the junction. Localization of the exciton within the junction area is accompanied by the appearance of the dipole moment induced by the local electric field. The induced dipole moment becomes a linear function of the potential step only when the step is sufficiently large. In consequence, the energy dependence on the step value is nonparabolic. We demonstrate that the exciton gets localized not exactly at the center of the junction but on the side which is more energetically favorable for the heavier carrier: electron or hole.

关键词： Confinement Excitons Stark effect 2-dimensional systems Variational approach

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Thermal properties of structurally balanced systems on diluted and densified triangulations

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Physical Review E 2022年第2期105卷 024301-024301页

作者： Maciej Wołoszyn Krzysztof Malarz AGH University of Science and Technology Faculty of Physics and Applied Computer Science al. Mickiewicza 30 30-059 Kraków Poland

The dynamics of social relations and the possibility of reaching the state of structural balance (Heider balance) are discussed for various networks of interacting actors under the influence of the temperature modeling the social noise level. For that purpose, two main types of lattices are considered. The first is created by removing some links from a regular triangular lattice to produce a diluted triangular lattice, and the second by adding more links to create an enhanced triangular lattice. In both those cases, the full range of possible graph densities is discussed, limited by the extreme cases of networks which consist of a small number of separated triads and fully connected networks. It is shown that the existence of the balanced state is not possible if the average node degree is too close to the value characterizing the regular triangular lattice. Otherwise, both balanced (or partially balanced) and imbalanced states are possible, depending on the temperature. However, only for graphs which are dense enough a phase transition of the first kind is observed, while less enhanced networks (and all diluted) indicate a smooth crossover between the two states. The crossover temperatures are size independent only for the diluted triangular lattices and depend on the size of the system for the enhanced triangular lattices, as is the case also for the critical temperatures of the phase transition observed in denser enhanced lattices.

关键词： Social systems Social dynamics Social networks

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A hybrid optimization approach for securing cloud-based e-health systems

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Multimedia Tools and Applications 2025年第16期84卷 16525-16560页

作者： Altherwi, Abdulhadi Ahmad, Mohammad Tauheed Alam, Md. Moddassir Mirza, Hidayath Sultana, Nazia Pasha, Amjad Ali Sultana, Nishat Khan, Asif Irshad Alam, Md Mottahir Azim, Rezaul Department of Industrial Engineering College of Engineering and Computer Science Jazan University PO Box. 706 Jazan45142 Saudi Arabia College of Medicine King Khalid University Abha Saudi Arabia Department of Health Information Management and Technology College of Applied Medical Sciences University of Hafr Al-Batin Hafr Al-Batin Saudi Arabia Department of Electrical and Electronic Engineering College of Engineering and Computer Science Jazan University Jazan45142 Saudi Arabia Government Medical College Siddipet Ensanpalli Siddipet District Telangana502114 India Aerospace Engineering Department King Abdulaziz University Jeddah21589 Saudi Arabia Department of Business Administration Applied College Jazan University P. O. Box 706 Jazan45142 Saudi Arabia Department of Computer Science Aligarh Muslim University Uttar Pradesh Aligarh202002 India Department of Electrical and Computer Engineering Faculty of Engineering King Abdulaziz Jeddah21589 Saudi Arabia Department of Physics University of Chittagong Chattogram4331 Bangladesh

In modern healthcare, cloud-based e-health technology offers substantial benefits but faces significant security challenges. Sensitive patient data is vulnerable to cyber threats during transmission and storage, potentially enabling unethical collaboration between healthcare professionals and cloud storage providers. This paper aims to develop a robust security framework that safeguards patient privacy and prevents unauthorized access to sensitive medical information in remote patient health monitoring systems. The study presents an Artificial Hybrid Optimization with an Attribute-Based Encryption (AHO-ABE) model. The model leverages cryptographic techniques and hybrid optimization to enhance data security. Specifically, whale optimization (WO) is used for efficient key generation, while sheep flock optimization (SFO) is employed for continuous network surveillance. Experimental results demonstrate that the AHO-ABE model significantly enhances data security, outperforming existing RPM-MEC, AID, AI-HCS, and IoT-HMS approaches. The model exhibits superior resilience against unauthorized access and data breaches, achieving a 5 ms execution time, 850 kbps throughput, 0.121 mJ energy usage, and 4 s latency. Combining cryptographic techniques with hybrid optimization algorithms, the AHO-ABE model provides a robust framework for safeguarding sensitive medical information. This approach ensures the integrity and confidentiality of patient data in remote healthcare settings, offering an effective solution against high-performance cyber attacks. © The Author(s), under exclusive licence to Springer science+Business Media, LLC, part of Springer Nature 2024.

关键词： Diagnosis

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Strong-field double ionization in a three-electron atom: Momentum-distribution analysis

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Physical Review A 2023年第3期108卷 033103-033103页

作者： Dmitry K. Efimov Artur Maksymov Jakub Zakrzewski Jakub S. Prauzner-Bechcicki Institute of Theoretical Physics Faculty of Fundamental Problems of Technology Wrocław University of Science and Technology 50-370 Wrocław Poland Institute of Theoretical Physics Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Stanisława Łojasiewicza 11 30-348 Kraków Poland Mark Kac Center for Complex Systems Research Jagiellonian University Stanisława Łojasiewicza 11 30-348 Kraków Poland Jagiellonian University in Kraków Faculty of Physics Astronomy and Applied Computer Science Marian Smoluchowski Institute of Physics Łojasiewicza 11 30-348 Krakow Poland

We study strong-field double ionization in a three-electron atom by applying a simplified, reduced-dimensionality model with three active electrons. The influence of the spin-induced symmetry of the spatial part of the wave function on the final two-photoelectron momentum distribution is discussed. We identify partial momentum distributions originating from different sets of spins of outgoing electrons providing in this way a quantum support connection between the V-structure and direct ionization typically explained classically. Changes in the momentum distribution with increasing field amplitude obtained in our simplified model are shown to be well correlated with the experimental data known from the literature. The possible relation between the observed dependencies and different ionization mechanisms is discussed.

关键词： Multiphoton or tunneling ionization & excitation Strong electromagnetic field effects Strong field excitation Ultrafast phenomena Atomic systems First-principles calculations Schroedinger equation

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Wigner molecules in phosphorene quantum dots

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Physical Review B 2022年第20期106卷 205304-205304页

作者： Tanmay Thakur Bartłomiej Szafran AGH University of Science and Technology Faculty of Physics and Applied Computer Science al. Mickiewicza 30 30-059 Kraków Poland

We study Wigner crystallization of electron systems in phosphorene quantum dots with the confinement of an electrostatic origin with both circular and elongated geometry. The large effective masses in phosphorene promote the separation of the electron charges already for quantum dots of relatively small size. The anisotropy of the effective mass allows for the formation of Wigner molecules in the laboratory frame with a confined charge density that has lower symmetry than the confinement potential. We find that in circular quantum dots separate single-electron islands are formed for two and four confined electrons but not for three trapped carriers. The spectral signatures of the Wigner crystallization to be resolved by transport spectroscopy are discussed. Systems with Wigner molecule states are characterized by a nearly degenerate ground state at B=0 and are easily spin-polarized by the external magnetic field. In electron systems for which the single-electron islands are not formed, a more even distribution of excited states at B=0 is observed, and the confined system undergoes ground-state symmetry transitions at magnetic fields of the order of 1 T. The system of five electrons in a circular quantum dot is indicated as a special case with two charge configurations that appear in the ground state as the magnetic field is changed: one with the single electron islands formed in the laboratory frame and the other where only the pair-correlation function in the inner coordinates of the system has a molecular form as for three electrons. The formation of Wigner molecules of quasi-1D form is easier for the orientation of elongated quantum dots along the zigzag direction with heavier electron mass. The smaller electron effective mass along the armchair direction allows for freezing out the transverse degree of freedom in the electron motion. Calculations are performed with a version of the configuration interaction approach that uses a single-electron basis that is preo

关键词： Coulomb blockade Localization 1-dimensional systems Quantum dots Wigner crystal Exact diagonalization Transport techniques Variational wave functional methods

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Atomistic Behavior of Deformed Au Thin Film during the Indentation Process 4

Atomistic Behavior of Deformed Au Thin Film during the Inden...

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4th International Conference on Innovative Research in applied science, Engineering and Technology, IRASET 2024

作者： Ou-Khouya, Abdelkarim Mes-Adi, Hassane Taoufiki, Meryem Ibrahim, Imane Ait El Harfouf, Amin Herbazi, Rachid Tahiri, Mohamed Khouribga National School Of Applied Sciences Sultan Moulay Slimane University Process Engineering Computer Science And Mathematics Laboratory Khouribga25000 Morocco Sultan Moulay Slimane University Faculty Of Sciences And Techniques Sustainable Development Laboratory Beni-Mellal Morocco Mohamed V University Laboratory Of Condensed Matter And Interdisciplinary Sciences Cnrst Labeled Research Unit Faculty Of Sciences Departement Of Physics Rabat Morocco University Of Sultan Moulay Slimane Polydisciplinary Faculty Of Khouribga Department Of Physics Khouribga Morocco Tangier Morocco

ISBN: (纸本)9798350309508

In this study, we investigate the mechanical properties of gold (Au) materials using molecular dynamics simulations. In this simulation, the nanoindentation process was performed to analyze the deformation defects and hardness properties of Au under different indentation velocities. The results suggest that the deformation behavior of the Au specimen was affected by different indentation velocities. These findings were confirmed by examining the load-displacement curve, which indicated elastic deformation through the appearance of a linear load-displacement relationship at low indentation velocities. In contrast, plastic deformation was identified by the presence of intensified serrations in the load-displacement curve at higher indentation velocities. Under such conditions, the hardness exhibited minimal variation when the indenter velocity increased from 5 mls to 10 mls. However, a significant increase in hardness was noted when the indentation velocity was further raised to 15 mls. © 2024 IEEE.

关键词： Molecular dynamics

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Mixed state entanglement from symmetric matrix inequalities

arXiv

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arXiv 2025年

作者： Rico, Albert Physics department Universitat Autònoma de Barcelona Bellaterra BarcelonaES-08193 Spain Faculty of Physics Astronomy and Applied Computer Science Institute of Theoretical Physics Jagiellonian University Kraków30-348 Poland

Recently, a toolkit of highly symmetric techniques employing matrix inequalities has been developed to detect entanglement in various ways. Here we concisely review these methods providing a unified framework, and expand them to a new family of positive maps with further detection capabilities. In the simplest case, we generalize the reduction map to detect more generic states using both multiple copies and local filters. Through the Choi-Jamiolkowski isomorphism, this family of maps leads to a construction of multipartite entanglement witnesses. Discussions and examples are provided regarding the detection of states with local positive partial transposition and the use of multiple copies. Copyright © 2025, The Authors. All rights reserved.

关键词： Quantum entanglement

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State-witness contraction

arXiv

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arXiv 2025年

作者： Rico, Albert Physics Department Universitat Autònoma de Barcelona Bellaterra BarcelonaES-08193 Spain Faculty of Physics Astronomy and Applied Computer Science Institute of Theoretical Physics Jagiellonian University Kraków30-348 Poland

We present a method to construct entanglement witnesses for arbitrarily large multipartite systems, by tensoring and partial tracing existing states and witnesses. As a proof of principle we show that, using little shared quantum resources, the method allows to reuse witnesses unable to detect states with local positive partial transpositions into new ones able to do so. Moreover, we show that this technique allows to tailor both linear and nonlinear witnesses to specific states using semidefinite programming with comparatively low-dimensional variables. As an example, existing trace polynomial witnesses are significantly improved while preserving their symmetries and implementability with randomized measurements. Besides detecting entanglement, the method is shown to detect k-copy distillability. A recipe for the single-copy case is shown to be effective for generic and Werner states. Copyright © 2025, The Authors. All rights reserved.

关键词： Quantum entanglement

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Lévy flights and Lévy walks under stochastic resetting

arXiv

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arXiv 2023年

作者： Zbik, Bartosz Dybiec, Bartlomiej Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Lojasiewicza 11 Kraków30-348 Poland Institute of Theoretical Physics Mark Kac Center for Complex Systems Research Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Lojasiewicza 11 Kraków30-348 Poland

Stochastic resetting is a protocol of starting anew, which can be used to facilitate the escape kinetics. We demonstrate that restarting can accelerate the escape kinetics from a finite interval restricted by two absorbing boundaries also in the presence of heavy-tailed, Lévy type, α-stable noise. However, the width of the domain where resetting is beneficial depends on the value of the stability index α determining power-law decay of jump length distribution. For heavier (smaller α) distributions the domain becomes narrower in comparison to lighter tails. Additionally, we explore connections between Lévy flights and Lévy walks in presence of stochastic resetting. First of all, we show that for Lévy walks, the stochastic resetting can be beneficial also in the domain where coefficient of variation is smaller than 1. Moreover, we demonstrate that in the domain where LW are characterized by a finite mean jump duration/length, with the increasing width of the interval LW start to share similarities with LF under stochastic resetting. Copyright © 2023, The Authors. All rights reserved.

关键词： Stochastic systems

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