Long-range Interactions Research Articles

Topological edge states in a Rydberg composite

We examine topological phases and symmetry-protected electronic edge states in the context of a Rydberg composite: a Rydberg atom interfaced with a structured arrangement of ground-state atoms. We show that the spectrum of the electronic Hamiltonian of such a composite possesses a mapping to that of a tight-binding Hamiltonian, which can exhibit nontrivial topology depending on the arrangement of the ground-state atoms and the principal quantum number of the Rydberg state. The Rydberg electron moves in a combined potential including the long-ranged Coulomb interaction with the Rydberg core and short-ranged interactions with each neutral atom; the effective hopping amplitudes between sites are determined by this combination. We first confirm the existence of topologically-protected edge states in a Rydberg composite by mapping it to the paradigmatic Su-Schrieffer-Heeger dimer model. Following that, we show that more complicated systems with trimer unit cells can be studied in a Rydberg composite. Published by the American Physical Society 2024

Separable graph Hamiltonian network: A graph deep learning model for lattice systems

Addressing the challenges posed by nonlinear lattice models, which are vital across diverse scientific disciplines, we present a new deep learning approach that harnesses the power of graph neural networks. By representing the lattice system as a graph and leveraging the graph structures to identify complex nonlinear relationships, we have developed a flexible solution that outperforms traditional techniques. Our model not only offers precise trajectory predictions and energy conservation properties by incorporating separable Hamiltonians but also proves superior to existing top-tier models when tested on classic nonlinear oscillator lattice problems: a mixed Fermi-Pasta-Ulam Klein-Gordon, a Klein-Gordon system with long-range interactions, and a two-dimensional Frenkel-Kontorova, highlighting its potential for wide-reaching applications. Published by the American Physical Society 2024

Molecular Insights into the Inhibition and Disaggregation Effects of EGCG on Aβ40 and Aβ42 Cofibrillation.

The misfolding and aggregation of amyloid-β (Aβ) peptides play a pivotal role in the pathogenesis of Alzheimer's disease (AD). Aβ40 and Aβ42, the two primary isoforms of Aβ, can not only self-aggregate into homogeneous aggregates but also coaggregate to form mixed fibrils. Epigallocatechin-3-gallate (EGCG), a prominent tea polyphenol, has shown the capability to prevent the self-aggregation of Aβ40 and Aβ42 peptides and disaggregate their homogeneous fibrils. However, its effects on the cofibrillation of Aβ40 and Aβ42 have not yet been explored. Here, we employed molecular dynamic simulations to investigate the effects of EGCG on the coaggregation of Aβ40 and Aβ42, as well as on their mixed fibril. Our findings indicated that EGCG effectively inhibits the codimerization of Aβ40 and Aβ42 primarily by impeding the interchain interaction between the two isoforms. The key binding sites for EGCG on Aβ40 and Aβ42 are the polar residues and aromatic residues, engaging in hydrogen-bond , π-π, and cation-π interactions with EGCG. Additionally, EGCG disaggregates the Aβ40-Aβ42 mixed fibril by reducing its long-range interaction through similar binding sites and interactions as those between EGCG and Aβ40-Aβ42 heterodimers. Our research reveals the comprehensive inhibition and disaggregation effects of EGCG on the cofibrillation of Aβ isoforms, which provides further support for the development of EGCG as an effective antiaggregation agent for AD.

Use of <i>q</i>-statistics for study of pulsating aurora

The non-extensive statistical mechanics method of Tsallis (or q-statistics) is first applied to study pulsating auroras, which are regularly observed in the auroral ionosphere during geomagnetic disturbances. For systems with long-range interactions, such as ionized gas or plasma, whose dynamics are primarily determined by long-range electromagnetic forces, one can expect that non-additive and non-extensive thermostatistical principles may characterize their macroscopic behavior. This paper shows that pulsating polar auroras exhibit non-extensive properties and can be described, in part, by q-statistics. It is also demonstrated that the non-extensive parameter q correlates well with the flatness coefficient and scaling index, indicating the applicability of this approach to auroral emissions. Thus, q-statistics can be used to analyze phenomena in the high-latitude region of the Earth.

Doping-dependent charge- and spin-density wave orderings in a monolayer of Pb adatoms on Si(111)

In this work we computed the phase diagram as a function of temperature and doping for a system of lead adatoms allocated periodically on a silicon (111) surface. This Si(111):Pb material is characterized by a strong and long-ranged Coulomb interaction, a relatively large value of the spin-orbit coupling, and a structural phase transition that occurs at low temperature. In order to describe the collective electronic behavior in the system, we perform many-body calculations consistently taking all these important features into account. We find that charge- and spin-density wave orderings coexist with each other in several regions of the phase diagram. This result is in agreement with the recent experimental observation of a chiral spin texture in the charge density wave phase in this material. We also find that the geometries of the charge and spin textures strongly depend on the doping level. The formation of such a rich phase diagram in the Si(111):Pb material can be explained by a combined effect of the lattice distortion and electronic correlations.

Thermal Teleportation of Accelerated Information Via XXX Two-Qubit Heisenberg Chain in the Presence of an Asymmetric External Magnetic Field with Long-Range Interaction

Thermal Teleportation of Accelerated Information Via XXX Two-Qubit Heisenberg Chain in the Presence of an Asymmetric External Magnetic Field with Long-Range Interaction

Application of Surface Stress-Driven Model for Higher Vibration Modes of Functionally Graded Nanobeams.

This paper employs a surface stress-driven nonlocal theory to investigate the synergistic impact of long-range interaction and surface energy on higher vibration modes of Bernoulli-Euler nanobeams made of functionally graded material. It takes into account surface effects such as the surface modulus of elasticity, residual surface stresses, surface density, and rotary inertia. The governing equation is derived through the application of Hamilton's principle. The novelty of this work lies in its pioneering approach to studying higher-order vibrations, carefully considering the combination of long-range interactions and surface energy in nanobeams of functionally graded materials through a well-posed mathematical model of nonlocal elasticity. This study conducts a parametric investigation, examining the effects of the nonlocal parameter and the material gradient index for four static schemes: Cantilever, Simply-Supported, Clamped-Pinned and Clamped-Clamped nanobeams. The outcomes are presented and discussed, highlighting the normalized nonlocal natural frequencies for the second through fifth modes of vibration in each case under study. In particular, this study illustrates the central role of surface effects in the dynamic response of nanobeams, emphasizing the importance of considering them. Furthermore, the parametric analysis reveals that the dynamic response is influenced by the combined effects of the nonlocal parameter, the material gradient index, the shapes of the cross-sections considered, as well as the static scheme analyzed.

Bright solitons in a spin-orbit-coupled dipolar Bose-Einstein condensate trapped within a double-lattice.

By effectively controlling the dipole-dipole interaction, we investigate the characteristics of the ground state of bright solitons in a spin-orbit coupled dipolar Bose-Einstein condensate. The dipolar atoms are trapped within a double-lattice which consists of a linear and a nonlinear lattice. We derive the motion equations of the different spin components, taking the controlling mechanisms of the dipole-dipole interaction into account. An analytical expression of dipole-dipole interaction is derived. By adjusting the dipole polarization angle, the dipole interaction can be adjusted from attraction to repulsion. On this basis, we study the generation and manipulation of the bright solitons using both the analytical variational method and numerical imaginary time evolution. The stability of the bright solitons is also analyzed and we map out the stability phase diagram. By adjusting the long-range dipole-dipole interaction, one can achieve manipulation of bright solitons in all aspects, including the existence, width, nodes, and stability. Considering the complexity of our system, our results will have enormous potential applications in quantum simulation of complex systems.

Ion Channels in Critical Membranes: Clustering, Cooperativity, and Memory Effects

Much progress has been made in elucidating the inner workings of voltage-gated ion channels, but less understood is the influence of lipid rafts on gating kinetics. Here we propose that state-dependent channel affinity for different lipid species provides a unified explanation for the experimentally observed behaviors of clustering, cooperativity, and hysteresis. We develop models of diffusing lipids and channels engaged in Ising-like interactions to investigate the collective behaviors driven by raft formation in critical membranes close to the demixing transition. The model channels demonstrate lipid-mediated long-range interactions, activation curve steepening, and long-term memory in ionic currents. These behaviors likely play a role in channel-mediated cellular signaling and suggest a universal mechanism for self-organization of biomolecular assemblies. Published by the American Physical Society 2024

Role of Interaction Range and Buoyancy on the Adhesion of Vesicles.

Vesicles on substrates play a fundamental role in many biological processes, ranging from neurotransmitter release at the synapse on small scales to the nutrient intake of trees by large vesicles. For these processes, the adsorption or desorption of vesicles to biological substrates is crucial. Consequently, it is important to understand the factors determining whether and for how long a vesicle adsorbs to a substrate and what shape it will adopt. Here, we systematically study the adsorption of a vesicle to planar substrates with short- and long-range interactions, with and without buoyancy. We assume an axially symmetric system throughout our simulations. Previous studies often considered a contact potential of zero range and neutral buoyancy. The interaction range alters the location and order of the adsorption transition and is particularly important for small vesicles, e.g., in the synapse. Whereas even small density differences between the inside and the outside of the vesicle give rise to strong buoyancy effects for large vesicles, e.g., giant unilamellar vesicles, as buoyancy effects scale with the fourth power of the vesicle size. We find that (i) an attractive membrane-substrate potential with nonzero spatial extension leads to a pinned state, where the vesicle benefits from the attractive membrane-substrate interaction without significant deformation. The adsorption transition is of first order and occurs when the substrate switches from repulsive to attractive. (ii) Buoyancy shifts the transversality condition, which relates the maximal curvature in the contact zone to the adhesion strength and bending rigidity, up/downward, depending on the direction of the buoyancy force. The magnitude of the shift is influenced by the range of the potential. For upward buoyancy, adsorbed vesicles are at most metastable. We determine the stability limit and the desorption mechanisms and compile the thermodynamic data into an adsorption diagram. Our findings reveal that buoyancy, as well as spatially extended interactions, are essential when quantitatively comparing experiments to theory.

Entanglement Generation of Polar Molecules via Deep Reinforcement Learning.

Polar molecules are a promising platform for achieving scalable quantum information processing because of their long-range electric dipole-dipole interactions. Here, we take the coupled ultracold CaF molecules in an external electric field with gradient as qubits and concentrate on the creation of intermolecular entanglement with the method of deep reinforcement learning (RL). After sufficient training episodes, the educated RL agents can discover optimal time-dependent control fields that steer the molecular systems from separate states to two-qubit and three-qubit entangled states with high fidelities. We analyze the fidelities and the negativities (characterizing entanglement) of the generated states as a function of training episodes. Moreover, we present the population dynamics of the molecular systems under the influence of control fields discovered by the agents. Compared with the schemes for creating molecular entangled states based on optimal control theory, some conditions (e.g., molecular spacing and electric field gradient) adopted in this work are more feasible in the experiment. Our results demonstrate the potential of machine learning to effectively solve quantum control problems in polar molecular systems.

Mitigating crosstalk errors by randomized compiling: Simulation of the BCS model on a superconducting quantum computer

We develop and apply an extension of the randomized compiling (RC) protocol that includes a special treatment of neighboring qubits and dramatically reduces crosstalk effects caused by the application of faulty gates on superconducting qubits in IBMQ quantum computers ( and ). Crosstalk errors, stemming from controlled- () two-qubit gates, are a crucial source of errors on numerous quantum computing platforms. For the IBMQ machines, their effect on the performance of a given quantum computation is often overlooked. Our RC protocol turns coherent noise due to crosstalk into a depolarizing noise channel that can then be treated using established error mitigation schemes, such as noise estimation circuits. We apply our approach to the quantum simulation of the nonequilibrium dynamics of the Bardeen-Cooper-Schrieffer (BCS) Hamiltonian for superconductivity, a particularly challenging model to simulate on quantum hardware because of the long-range interaction of Cooper pairs. With 135 gates, we work in a regime where crosstalk, as opposed to either Trotterization or qubit decoherence, dominates the error. Our twirling of neighboring qubits is shown to dramatically improve the noise estimation protocol without the need to add new qubits or circuits and allows for a quantitative simulation of the BCS model. Published by the American Physical Society 2024

Critical analysis of skyrmionic material Co6.5Ru1.5Zn8Mn4: A complex interplay of short and long-range interactions around the transition temperature

In contrast to the critical behaviour study in magnetism which is well known and important owing to its application for understanding the nature of underlying spin-spin interactions, magnetotransport based critical studies are rare in literature, although it has advantages from bulk to mesoscopic magnetic devices. In this article, we report the novel manifestation of crossover behaviour between two universality classes governing spin interaction across the ferromagnetic Curie temperature TC in critical scaling of anomalous hall conductivity (AHC) isotherms for a skyrmion-hosting itinerant ferromagnet Co6.5Ru1.5Zn8Mn4. Along with the magnetotransport, the traditional critical scaling of magnetic isotherms yields β = 0.423 ± 0.004, γ = 1.08 ± 0.016, and δ = 3.553 ± 0.009 suggesting the 3D Heisenberg and Mean Field type of spin interactions below and above TC, respectively. The isotropic magnetic exchange strength decays as J(r) ≈ r−4.617, implying the prevalence of crossover from long-range ordering to short-range type interaction. In addition, the existence of a fluctuation-disordered magnetic phase immediately below TC and a skyrmion pocket bounded by conical-helical phases have been observed in the magnetocaloric effect. The novel approach of generating a low-field phase diagram employing the quantitative criterion of phase transition from the scaling of isothermal magneto-entropic change (ΔSm) shows an excellent convergence with the phase boundaries obtained from conventional magnetic and AHC scaling. This simultaneous scaling of magnetization and AHC isotherms for systems with crossover behaviour establishes the universality of the magnetotransport-based critical scaling approach which still remains in its infancy.

Mechanosensitivity of phase separation in an elastic gel

Liquid–liquid phase separation (LLPS) in binary or multi-component solutions is a well-studied subject in soft matter with extensive applications in biological systems. In recent years, several experimental studies focused on LLPS of solutes in hydrated gels, where the formation of coexisting domains induces elastic deformations within the gel. While the experimental studies report unique physical characteristics of these systems, such as sensitivity to mechanical forces and stabilization of multiple, periodic phase-separated domains, the theoretical understanding of such systems and the role of long-range interactions have not emphasized the nonlinear nature of the equilibrium binodal for strong segregation of the solute. In this paper, we formulate a generic, mean-field theory of a hydrated gel in the presence of an additional solute which changes the elastic properties of the gel. We derive equations for the equilibrium binodal of the phase separation of the solvent and solute and show that the deformations induced by the solute can result in effective long-range interactions between phase-separating solutes that can either enhance or, in the case of externally applied pressure, suppress phase separation of the solute relative to the case where there is no gel. This causes the coexisting concentrations at the binodal to depend on the system-wide average concentration, in contrast to the situation for phase separation in the absence of the gel.Graphical abstract

Limiting dynamics of stochastic complex Ginzburg–Landau lattice systems with long-range interactions in weighted space

This paper deals with the limiting dynamics of stochastic complex Ginzburg–Landau lattice systems with long-range interactions driven by nonlinear noise in a weighted space L2(Ω,lη2). We first consider the well-posedness of solutions for considered stochastic systems in the weighted space and then establish the existence and uniqueness of weak pullback mean random attractor in the weighted space.

Long-range RNA interactions in flavivirus replication

Long-range RNA interactions in flavivirus replication

Implementing the spherical grids and treecode algorithm for efficient parallelization of long-range electrostatic interactions

Implementing the spherical grids and treecode algorithm for efficient parallelization of long-range electrostatic interactions

Effect of Long-Range Interaction in the Modification of Near-Surface Layers of WC–Co Samples by Pulsed Ion Beam

Effect of Long-Range Interaction in the Modification of Near-Surface Layers of WC–Co Samples by Pulsed Ion Beam

Promoter-centred chromatin interactions associated with EVI1 expression in EVI1+3q- myeloid leukaemia cells.

EVI1 expression is associated with poor prognosis in myeloid leukaemia, which can result from Chr.3q alterations that juxtapose enhancers to induce EVI1 expression via long-range chromatin interactions. More often, however, EVI1 expression occurs unrelated to 3q alterations, and it remained unclear if, in these cases, EVI1 expression is similarly caused by aberrant enhancer activation. Here, we report that, in EVI1+3q- myeloid leukaemia cells, the EVI1 promoter interacts via long-range chromatin interactions with promoters of distally located, active genes, rather than with enhancer elements. Unlike in 3q+ cells, EVI1 expression and long-range interactions appear to not depend on CTCF/cohesin, though EVI1+3q- cells utilise an EVI1 promoter-proximal site to enhance its expression that is also involved in CTCF-mediated looping in 3q+ cells. Long-range interactions in 3q- cells connect EVI1 to promoters of multiple genes, whose transcription correlates with EVI1 in EVI1+3q- cell lines, suggesting a shared mechanism of transcriptional regulation. In line with this, CRISPR interference-induced silencing of two of these sites minimally, but consistently reduced EVI1 expression. Together, we provide novel evidence of features associated with EVI1 expression in 3q- leukaemia and consolidate the view that EVI1 in 3q- leukaemia is largely promoter-driven, potentially involving long-distance promoter clustering.

Vibrational Dipole-Dipole Coupling and Long-Range Forces between Macromolecules.

Long-range interactions between biomacromolecules are considered important for directing intracellular processes. Recent studies have posited that interactions between oscillating dipoles are well-suited to mediating long-range forces because they are weakly screened by a dielectric environment. Here, we extend these studies and present a quantum electrodynamic mechanism for resonant interactions between vibrational transition dipole moments of molecules. We explicitly consider the molecular charge density oscillations as IR transition dipoles. This gives a physical, molecular assignment to the idea of oscillating dipoles and allows us to develop explicit expressions for the interactions that can be quantified using parameters known from experiment. Moreover, in the same framework, we can describe van der Waals forces. We use numerical calculations to estimate the strength of resonant vibrational dipole-dipole interactions over long distances and compare these estimates to the van der Waals interaction. We find that the resonant vibrational dipole-dipole interactions dominate over the long range.