Attractive Coupling Research Articles

Phases and dynamics of few fermionic impurities immersed in two-dimensional boson droplets

We unravel the ground state properties and emergent nonequilibrium dynamics of a mixture consisting of a few spin-polarized fermions embedded in a two-dimensional bosonic quantum droplet. For an increasingly attractive droplet-fermion interaction we find a transition from a spatially delocalized fermion configuration to a state where the fermions are highly localized and isolated. This process is accompanied by the rise of induced fermion-fermion interactions mediated by the droplet. Additionally, for increasing attractive droplet-fermion coupling, undulations in the droplet density occur in the vicinity of the fermions manifesting the back-action of the latter. Following interaction quenches from strong to weaker attractive droplet-fermion couplings reveals the spontaneous nucleation of complex excitation patterns in the fermion density such as ring- and cross-shaped structures. These stem from the enhanced interference of the fermions that remain trapped within the droplet, which emulates, to a good degree, an effective potential for the fermions. The non-negligible back-action of the droplet manifests itself in the fact that the effective potential predictions are less accurate at the level of the many-body wave function. Our results provide a paradigm for physics beyond the reduced single-component droplet model, unveiling the role of back-action in droplets and the effect of induced mediated interactions. Published by the American Physical Society 2024

Realization of logic gates in bi-directionally coupled nonlinear oscillators.

Implementation of logic gates has been investigated in nonlinear dynamical systems from various perspectives over the years. Specifically, logic gates have been implemented in both single nonlinear systems and coupled nonlinear oscillators. The majority of the works in the literature have been done on the evolution of single oscillators into OR/AND or NOR/NAND logic gates. In the present study, we demonstrate the design of logic gates in bi-directionally coupled double-well Duffing oscillators by applying two logic inputs to the drive system alone along with a fixed bias. The nonlinear system, comprising both bi-directional components, exhibits varied logic behaviors within an optimal range of coupling strength. Both attractive and repulsive couplings yield similar and complementary logic behaviors in the first and second oscillators. These couplings play a major role in exhibiting fundamental and universal logic gates in simple nonlinear systems. Under a positive bias, both the first and second oscillators demonstrate OR logic gate for the attractive coupling, while exhibiting OR and NOR logic gates, respectively, for the repulsive coupling. Conversely, under a negative bias, both the first and second oscillators display AND logic gate for the attractive coupling, and AND and NAND logical outputs for the repulsive coupling. Furthermore, we confirm the robustness of the bi-directional oscillators against moderate noise in maintaining the desired logical outputs.

Chimera states in fractional-order coupled Rayleigh oscillators

Chimera states, characterized by the coexistence of synchronized and desynchronized oscillators, have been extensively described via integer differential equations over the past few decades. However, it is still unclear whether and under which conditions chimera states will appear in terms of the coupled systems involving fractional derivatives. In this work, we investigate the chimera states of Rayleigh oscillators in the fractional-order systems with attractive and repulsive couplings. Firstly, we introduce the repulsive control factor and show the various transition routes from the desynchronized state to the incoherent oscillation death by altering this factor and the fractional-order derivatives. Then, it is demonstrated that as the coupling strength varies, a vast repertoire of interesting collective behaviors will emerge, such as synchronization, solitary state, traveling wave, traveling chimera, oscillatory cluster, imperfect traveling chimera state, imperfect amplitude chimera state, and chimera death. Finally, we discuss the effect of attractive and repulsive couplings and find that decreasing the repulsive control factor can reduce the repulsive interaction, allowing the attractive coupling to dominate and promote the emergence of the coherent state.

Cluster formation due to repulsive spanning trees in attractively coupled networks.

Ensembles of coupled nonlinear oscillators are a popular paradigm and an ideal benchmark for analyzing complex collective behaviors. The onset of cluster synchronization is found to be at the core of various technological and biological processes. The current literature has investigated cluster synchronization by focusing mostly on the case of attractive coupling among the oscillators. However, the case of two coexisting competing interactions is of practical interest due to their relevance in diverse natural settings, including neuronal networks consisting of excitatory and inhibitory neurons, the coevolving social model with voters of opposite opinions, and ecological plant communities with both facilitation and competition, to name a few. In the present article, we investigate the impact of repulsive spanning trees on cluster formation within a connected network of attractively coupled limit-cycle oscillators. We successfully predict which nodes belong to each cluster and the emergent frustration of the connected networks independent of the particular local dynamics at the network nodes. We also determine local asymptotic stability of the cluster states using an approach based on the formulation of a master stability function. We additionally validate the emergence of solitary states and antisynchronization for some specific choices of spanning trees and networks.

Validity of annealed approximation in a high-dimensional system

This study investigates the suitability of the annealed approximation in high-dimensional systems characterized by dense networks with quenched link disorder, employing models of coupled oscillators. We demonstrate that dynamic equations governing dense-network systems converge to those of the complete-graph version in the thermodynamic limit, where link disorder fluctuations vanish entirely. Consequently, the annealed-network systems, where fluctuations are attenuated, also exhibit the same dynamic behavior in the thermodynamic limit. However, a significant discrepancy arises in the incoherent (disordered) phase wherein the finite-size behavior becomes critical in determining the steady-state pattern. To explicitly elucidate this discrepancy, we focus on identical oscillators subject to competitive attractive and repulsive couplings. In the incoherent phase of dense networks, we observe the manifestation of random irregular states. In contrast, the annealed approximation yields a symmetric (regular) incoherent state where two oppositely coherent clusters of oscillators coexist, accompanied by the vanishing order parameter. Our findings imply that the annealed approximation should be employed with caution even in dense-network systems, particularly in the disordered phase.

Hamilton energy variations in memristive Hindmarsh–Rose neurons under attractive and repulsive couplings

Hamilton energy variations in memristive Hindmarsh–Rose neurons under attractive and repulsive couplings

Surface effect on the phase separation in thin liquid crystal film as seen from a mean-field approach

The effect of the interplay between attractive nonlocal surface interactions and attractive pair long-range intermolecular couplings on molecular structures of liquid crystals confined in thin cells with flat solid surfaces has been studied. It has been shown, in the framework of the extended McMillan′s mean field theory, that in the confined LC system a complex orientational and translational ordering of molecules can be induced. Several scenarios of the formation of local smectic A, nematic, and isotropic phases have been shown to coexist in a certain temperature range. Due to the nonlocality of the surface interaction, an unexpected complexity of the spatial arrangement of these local phases along the direction of the normal to the surface may exhibit itself.

Cyclops states in repulsive theta-neuron networks

Networks of phase oscillators have become a widely established paradigmatic model for studying emergent collective behavior across several real-world systems, including neuronal networks, populations of chemical oscillators, and power grids. The Kuramoto model, involving one-dimensional or two-dimensional phase oscillators, demonstrates the potential for networks to showcase exceptional collective dynamics. This encompasses various outcomes such as full, partial, explosive, and asymmetry-induced synchronization, clusters, chimeras, solitary states, and generalized splay states. Notably, increasing all-to-all coupling in the classical Kuramoto model induces full synchronization as the most probable outcome and dominant rhythm. Kuramoto networks with repulsive coupling usually display splay, generalized, and cluster splay states, but the conditions under which a certain rhythm can arise and prevail are not entirely understood. Equally important for connecting Kuramoto networks to practical physical systems is understanding the function of higher-order coupling terms. These terms display a Fourier decomposition of a general 2π-periodic interaction function [1]. Previous studies have demonstrated that the inclusion of higher-order terms in the classical Kuramoto model of oscillators with all-to-all attractive coupling can lead to multiple synchronous states and switching between synchronization clusters. However, the impact of higher-order coupling modes on rhythm generation in repulsive networks remains unexplored. In this work, we present significant progress in addressing the critical issue related to repulsive Kuramoto–Sakaguchi networks of phase oscillators with phase-lagged first-order and higher-order coupling. We demonstrate that weakly repulsive networks of even and odd numbers of oscillators with first-order coupling are dominated by two-cluster and three-cluster splay states, respectively. The three-cluster splay states consist of two distinct coherent clusters and one solitary oscillator. These tripod states can be considered a fusion of a two-body chimera and a solitary state. We have dubbed these patterns of three oscillators as “Cyclops states” in reference to the Greek mythological giant with a single eye. The solitary oscillator and synchronous clusters respectively represent the Cyclops’ eye and shoulders. We present a remarkable discovery that the inclusion of higher-order coupling modes leads to worldwide stability of cyclops states across almost the entire range of the phase-lag parameter controlling repulsion [2]. Beyond the Kuramoto oscillators, we demonstrate the robust presence of this effect in networks of canonical theta-neurons with adaptive coupling. Furthermore, our results provide insight into identifying dominant rhythms within repulsive physical and biological networks.

Characterization of an N-Allylglyoxylamide-Based Bioorthogonal Nitrone Trap.

Aldehydes are attractive bioorthogonal coupling partners. The ease of manipulation of aldehydes and their orthogonality to other classes of bioorthogonal reactions have inspired the exploration of chemistries, which generate irreversible conjugates. Similarly, nitrones have been shown to be potent 1,3-dipoles in bioorthogonal reactions when paired with strained alkynes. Here, we combine the reactivity of nitrones with the simplicity of aldehydes using an N-allylglyoxylamide, in a cascade reaction with an N-alkylhydroxylamine to produce a bicyclic isoxazolidine. The reaction is found to be catalyzed by 5-methoxyanthranilic acid and proceeds at pH 7 with favorable kinetics. Using the HaloTag7 protein bearing an N-alkylhydroxylamine, we show the reaction to be bioorthogonal in a complex cell lysate and to proceed well at the surface of a HEK293 cell. Furthermore, the reaction is compatible with a typical strain-promoted alkyne-azide click reaction. The characteristics of this reaction suggest it will be a useful addition to the pallet of bioorthogonal reactions that have revolutionized chemical biology.

Phase transitions on a multiplex of swarmalators.

Dynamics of bidirectionally coupled swarmalators subject to attractive and repulsive couplings is analyzed. The probability of two elements in different layers being connected strongly depends on a defined vision range r_{c} which appears to lead both layers in different patterns while varying its values. Particularly, the interlayer static sync π has been found and its stability is proven. First-order transitions are observed when the repulsive coupling strength σ_{r} is very small for a fixed r_{c} and, moreover, in the absence of the repulsive coupling, they also appear for sufficiently large values of r_{c}. For σ_{r}=0 and for sufficiently small values of r_{c}, both layers achieve a second-order transition in a surprising two steps that are characterized by the drop of the energy of the internal phases while increasing the value of the interlayer attractive coupling σ_{a} and later a smooth jump, up to high energy value where synchronization is achieved. During these transitions, the internal phases present rotating waves with counterclockwise and later clockwise directions until synchronization, as σ_{a} increases. These results are supported by simulations and animations added as supplemental materials.

Fast Lithium Ion Transport Pathways Constructed by Two-Dimensional Boron Nitride Nanoflakes in Quasi-Solid-State Polymer Electrolyte.

Quasi-solid-state electrolytes (QSSEs) are gaining huge popularity because of their significantly improved safety performance over nonaqueous liquid electrolytes and superior process adaptability over all-solid-state electrolytes. However, because of the existence of liquid molecules, QSSEs typically have low lithium ion transference numbers and compromised thermal stability. In this work, we present the fabrication of a well-rounded QSSE by introducing hexagonal boron nitride nanoflakes (BNNFs) as an inorganic filler in a poly(vinylene carbonate) matrix. BNNFs, in contrast to most inorganic fillers used as anion trappers, are used to build fast lithium ion transport pathways directly on their two-dimensional surfaces. We confirm the attractive coupling between lithium ions and BNNFs, and we confirm that with the help of BNNFs, lithium ions can migrate with less damping and a lower transport energy barrier. As a result, the designed electrolyte exhibits good ion transportability, promoted fire retardancy, and good compatibility with lithium metal anodes and commercial cathodes.

Configuration modulation of vermiculite by exfoliation coupled Cu(II) anchoring for boosting removal of tetracycline via synergy of adsorption and photocatalysis

Integrated adsorption and photocatalysis is a worth frontier strategy for recalcitrant organics elimination, yet the current challenge is developing materials featured with dual functions of adsorption/photocatalytic ability. In this scenario, a novel attractive exfoliated vermiculite coupling with Cu(II) composite (eVT@Cu) was tactfully engineered. Specifically, exfoliated structure containing vast negative charge was conductive for Cu(II) loading. The anchored Cu(II) played triple roles in this system, that is, regulating electron configuration of photocatalyst with narrow bandgap, as well as providing complexation sites for tetracycline (TC) enrichment. With the help of inherent Fe(III), Cu(II) was readily to form heterogeneous high-valence Cu(III) driven by photonic energy. Benefited by these effects, eVT@Cu exhibited extremely augment on TC removal compared to pristine VT and eVT, with ca. 80% removal efficiency through the synergy of adsorption and photocatalysis. Overall, this study not only provides an excellent environmental candidate for TC removal but also opens a brand-new perspective for the generation of heterogeneous high-valence Cu(III) over eVT@Cu under visible light.

Hierarchical coupling control of cable-driven multi-loop crane for underactuated positioning

For the low-cost anti-swing retrofit of existing offshore heavy cranes, a (2-UPPU/UPU)UP multi-loop configuration with six cable-driven prismatic pairs and a UP underactuated pendulum is introduced. Each UPPU branch contains a fast-moving prismatic pair and a slow-moving one. A configuration tracking method utilizing three slow cable motions in 2-UPPU/UPU is proposed by motion compensation technology. A multi-loop underactuated end positioning scheme is given to achieve the cargo's horizontal positioning in inertia frame, i.e., two fast cable motions in 2-UPPU are used to drive four states comprising their tracking trajectories and two cargo swings, which frees the wave compensation and swing suppression task from crane joints and retains the original crane system. A hierarchical coupling controller with a special coupling relation matrix is designed, where the matrix-based sub-controller fusion technique provides a standardized design approach with distinct physical meaning for the application of hierarchical methodology in underactuated multi-loop systems. The stability analysis by Lyapunov method reveals multiple coupling relation matrices matching stability conditions, giving birth to five attractive coupling control modes. Simulations and experiments are conducted to compare and verify performance.

Traces of electron-phonon coupling in one-dimensional cuprates

The appearance of certain spectral features in one-dimensional (1D) cuprate materials has been attributed to a strong, extended attractive coupling between electrons. Here, using time-dependent density matrix renormalization group methods on a Hubbard-extended Holstein model, we show that extended electron-phonon (e–ph) coupling presents an obvious choice to produce such an attractive interaction that reproduces the observed spectral features and doping dependence seen in angle-resolved photoemission experiments: diminished 3kF spectral weight, prominent spectral intensity of a holon-folding branch, and the correct holon band width. While extended e–ph coupling does not qualitatively alter the ground state of the 1D system compared to the Hubbard model, it quantitatively enhances the long-range superconducting correlations and suppresses spin correlations. Such an extended e–ph interaction may be an important missing ingredient in describing the physics of the structurally similar two-dimensional high-temperature superconducting layered cuprates, which may tip the balance between intertwined orders in favor of uniform d-wave superconductivity.

Regio and Stereoselective One-Pot Synthesis of 2-Deoxy-3-thio Pyranoses and Their O-Glycosides from Glycals.

A reaction of glycals with two different types of nucleophiles in the presence of SnCl4 enabled one-pot rapid access to 2-deoxy-3-thio pyranoses and their O-glycosides. The process involves thioaryl substitution at C-3 with stereoretention and α-selective O-glycosylation at C-1 from d-glycals, thus combining two reactions with three interventions. The present methodology features an attractive three-component coupling (1:1.2:1.5 ratio) with operational simplicity at 0 °C in 10-20 min. This stereoselective one-pot 1,3-difunctionalization approach of glycals is compatible with wide range of primary and secondary alcohols affording products in good to excellent yields. This methodology was successfully extended toward disaccharide synthesis. Several control experiments suggested a plausible reaction mechanism and rationale behind regio and stereoselectivity. The reaction strategy possesses an intrinsic ability for the synthesis of various natural products and drug molecules.

Dynamic Survivability in Nonlinear Oscillation Systems with Attractive–Repulsive Interaction

On the basis of global and BA scale-free coupled Stuart–Landau models, dynamic survivability has been investigated in detail with new definition and measure function, which is different from the previous survivability studies which only focused on static analysis. The effects on dynamic survivability of attractive–repulsive interaction and attack strategies are detected. Our results suggest that the coupling strength and presence of the repulsive interaction reduce the dynamic survivability in globally coupled systems. Furthermore, the dynamic survivability of the BA systems remains stable in the case of random attack with invariable critical attack cost [Formula: see text]. While they have the same features with globally coupled systems when being deliberately attacked; attacking high-degree oscillators show a tendency to spoil the dynamic survivability more effectively. Finally, it is found that the attractive coupling plays a more important role in the dynamic survivability. These findings may help us to prevent systems from being attacked and design survivable systems.

Explosive synchronization in phase oscillator populations with attractive and repulsive adaptive interactions

The attractive and repulsive adaptive coupling schemes among dynamical agents are ubiquitous in systems ranging from physics, biology to neuroscience, which have attracted increasing interest and ample attention during recent years. Here, we extend the classical Kuramoto model to the coupling with mixed signs by considering a particular adaptive scheme in a system of globally coupled phase oscillators. The time-varying coupling weight between each pair of oscillators is correlated with the local coherence that involves according to a nonlinear differential equation. The studied model is capable of capturing the essential properties of the explosive synchronization induced by the adaptive interactions. We carry out extensive simulations to explore the collective dynamics in different perspectives. Remarkably, we reveal that the occurrence of the abrupt transitions of the macroscopic overall weights, as well as the emergence of the correlations between the microscopic structure features (including degrees and frequency dissasortativity) and local dynamics trigger the explosive synchronization, which manifests the suppression rule for the formation of small synchronized clusters. Furthermore, we provide an analytical treatment for the reduced system that allows us to grasp the underlying mechanism of the observed phenomena. Our study can deepen the understanding of the explosive synchronization transitions and other related abrupt dynamic phenomena occurring in networked oscillators with generic adaptive schemes.

Chemical friction along the minor groove of DNA facilitates enzymatic translocation of λ-exonuclease via electrostatic ratchet.

DNA is a long polymeric substrate that provides specific binding sites for many proteins in cell nucleus. Both diffusion and directed translocation play an essential role for protein-DNA interactions in gene regulation processes but it is still not fully understood how specific proteins move and search their target sites in the myriad of DNA sequence repertoires. We use λ-exonuclease as a model of nucleic acid-molecular motors that processively translocates along the DNA. Here, we combined single molecule FRET and molecular dynamics (MD) simulation to examine how the dynamic interaction translates into overall enzymatic activity. Transient coupling between λ-exonuclease and its substrate DNA significantly alters its translocation by a factor of ∼30 due to chemical friction between a positive reside (ARG45) of the protein and electrostatic potential (EP) along the minor groove of DNA. Repulsive interaction gives rise to futile slippage events whereas attractive coupling between ARG45 and adenines at the minor grooves provides chemical ratcheting for unidirectional translocation, preventing diffusive backtracking by electrostatic friction. We propose an anti-friction-based ratchet for processive translocation. Our study provides new insights into not only interplay between dynamic chemophysical interaction and enzyme activity but also a role of the minor groove in regulating enzymatic activity based on DNA sequences.

Emergent behaviors of two attractively coupled swarm sphere models with frustration

We study the collective behaviors of an attractively coupled system of swarm sphere models. The swarm sphere model is a prototype particle model describing the aggregate dynamics of particles on a sphere under suitable conditions on system parameters and initial data. In this paper, we investigate emergent dynamics resulting from the attractive coupling of two swarm sphere models with heterogeneous system parameters such as natural frequency matrices, frustration matrices, and inter and intra coupling strengths. Due to the intricate interplay between system parameters, several collective behaviors of the whole mixed ensemble emerge. To this end, we provide several sufficient frameworks leading to the local and global aggregation dynamics that can be achieved in both complete and practical senses. The proposed frameworks are formulated in terms of system parameters and initial data, and we provide local and global aggregation estimates within the proposed frameworks. As a direct application of emergent dynamics, we show that the swarm sphere model with a uniform frustration is uniformly $ \ell_2 $-stable with respect to initial data.

Collective Dynamical Behaviors of Nonlocally Coupled Brockett Oscillators

In this study, we consider a network of nonlocally coupled Brockett oscillators (BOs) with attractive and repulsive (AR) couplings to illustrate the existence of diverse collective dynamical behaviors, whereas previous studies solely concentrated on synchronization. In the absence of coupling, the individual BO oscillator shows stable periodic oscillations (POs) or stable steady state (SS) depending on the critical values of the parameters. We first begin by examining the collective dynamics by setting the critical value of the parameters at the active (PO) region. A diverge collective dynamical states are manifested for a fixed nonlocal coupling range with rising coupling magnitude. Notably, the lower coupling strength exhibits two distinct dynamical patterns at lower and higher transients. At lesser transients, for example, transient dynamics of desynchronization, chimera, and traveling wave states are observed. At larger time periods, the transient dynamics disappear with the emergence of a synchronized state. Increasing the coupling strength results in a unique state of traveling wave or synchronized state for smaller and larger time periods depending on the coupling strength. Increasing the coupling strength further gives rise to clustering behaviors. Importantly, the considered system attains cluster oscillation death (COD) through a cluster oscillatory state (COS). Finally, there exists a chimera death at a larger coupling strength. The observed dynamical transitions are further demonstrated through the two‐parameter analysis by setting different critical thresholds.