Programmable Charge Transport in a Multichannel Single-Molecule Parallel Circuit.

Advances in molecular electronics focus on developing miniaturized electronic devices by leveraging molecules as fundamental building blocks. This approach exploits the unique structural properties of molecules and the robustness of their interfacial interactions with electrodes to achieve enhanced functionalities at the nanoscale. Achieving optimal balance between strong and weak interfacial couplings in molecular‐scale devices to reconcile competing performance and stability requirements remains a significant scientific challenge. Here, we introduce a hybrid coupling strategy utilizing multichannel parallel circuits to integrate the stability of strong coupling with the high‐energy molecular orbitals of weak coupling. Through precise mechanical modulation of interfacial coupling, we demonstrate programmable ternary switching and storage devices, achieving On/Off ratios exceeding 102 and switching frequencies up to 950 Hz via tip manipulation experiments. This investigation illuminates the complex dynamics of interfacial coupling in molecular devices and proposes a promising approach to optimize device stability and functionality by harmonizing strong and weak coupling in multichannel parallel circuits.

Short laser pulse amplification via stimulated Brillouin backscattering in plasma is considered. Previous work distinguishes between the weakly and strongly coupled regime and treats them separately. It is shown here that such a separation is not generally applicable because strong and weak coupling interaction regimes are entwined with each other. An initially weakly coupled amplification scenario may dynamically transform into strong coupling. This happens when the local seed amplitude grows and thus triggers the strongly driven plasma response. On the other hand, when in a strong coupling scenario, the pump pulse gets depleted, and its amplitude might drop below the strong coupling threshold. This may cause significant changes in the final seed pulse shape. Furthermore, experimentally used pump pulses are typically Gaussian-shaped. The intensity threshold for strong coupling may only be exceeded around the maximum and not in the wings of the pulse. Also here, a description valid in both strong and weak coupling regimes is required. We propose such a unified treatment which allows us, in particular, to study the dynamic transition between weak and strong coupling. Consequences for the pulse forms of the amplified seed are discussed.

THEORY OF STATIC AND DYNAMIC PROPERTIES OF SUPERLATTICES WITH FERROMAGNETIC AND ANTIFERROMAGNETIC COUPLING

Scaling Mount Planck II: Base Camp

We give an updated overview of both weak and strong coupling methods to describe the approach to a plasma described by viscous hydrodynamics, a process now called hydrodynamisation. At weak coupling the very first moments after a heavy ion collision is described by the colour-glass condensate framework, but quickly thereafter the mean free path is long enough for kinetic theory to become applicable. Recent simulations indicate thermalization in a time t∼40(η/s)4/3/T [L. Keegan, A. Kurkela, P. Romatschke, W. van der Schee, Y. Zhu, Weak and strong coupling equilibration in nonabelian gauge theories, JHEP 04 (2016) 031. arXiv:1512.05347, doi:10.1007/JHEP04(2016)031], with T the temperature at that time and η/s the shear viscosity divided by the entropy density. At (infinitely) strong coupling it is possible to mimic heavy ion collisions by using holography, which leads to a dual description of colliding gravitational shock waves. The plasma formed hydrodynamises within a time of 0.41/T recent extension found corrections to this result for finite values of the coupling, when η/s is bigger than the canonical value of 1/4π, which leads to t∼(0.41+1.6(η/s−1/4π))/T [S. Grozdanov, W. van der Schee, Coupling constant corrections in holographic heavy ion collisions, arXiv:1610.08976]. Future improvements include the inclusion of the effects of the running coupling constant in QCD.

Coupled systems subject to dissipation exhibit two different regimes known as weak coupling and strong coupling. Two damped coupled harmonic oscillators (CHOs) constitute a model system where the key features of weak and strong coupling can be identified. Several of these features are common to classical and quantum systems, as a number of quantum-classical correspondences have shown. However, the condition defining the boundary between weak and strong coupling is distinct in classical and quantum formalisms. Here we describe the origin of two widely used definitions of strong coupling. Using a classical CHO model, we show that energy exchange cycles and avoided resonance crossings signal the onset of strong coupling according to one criterion. From the classical CHO model we derive a non-Hermitian Hamiltonian describing open quantum systems. Based on the analytic properties of the Hamiltonian, we identify the boundary between weak and strong coupling with a different feature: a non-Hermitian degeneracy known as the exceptional point. For certain parameter ranges the classical and quantum criterion for strong coupling coincide; for other ranges they do not. Examples of systems in strong coupling according to one or another criterion, but not both, are illustrated. The framework here presented is suitable for introducing graduate or advanced undegraduate students to the basic properties of strongly coupled systems, as well as to the similarities and subtle differences between classical and quantum descriptions of coupled dissipative systems.

We use the stochastic series expansion quantum Monte Carlo method to study the Heisenberg models on the square lattice with strong and weak couplings in the form of three different plaquette arrangements known as checkerboard models C$2\times2$, C$2\times4$ and C$4\times4$. The $a\times b$ here stands for the shape of plaquette consisting with spins connected by strong couplings. Through detailed analysis of finite-size scaling study, the critical point of C$2\times2$ model is improved as $g_{c}=0.548524(3)$ compared with previous studies with $g$ to be the ratio of weak and strong couplings in the models. For C$2\times4$ and C$4\times4$ we give $g_{c}=0.456978(2)$ and $0.314451(3)$. We also study the critical exponents $\nu$, $\eta$, and the universal property of Binder ratio to give further evidence that all quantum phase transitions in these three models are in the three-dimensional O(3) universality class. Furthermore, our fitting results show the importance of effective corrections in the scaling study of these models.

By weakly gauging one of the U(1) subgroups of the R-symmetry group, = 4 super-Yang-Mills theory can be coupled to electromagnetism, thus allowing a computation of photon production and related phenomena in a QCD-like non-Abelian plasma at both weak and strong coupling. We compute photon and dilepton emission rates from finite temperature = 4 supersymmetric Yang-Mills plasma both perturbatively at weak coupling to leading order, and non-perturbatively at strong coupling using the AdS/CFT duality conjecture. Comparison of the photo-emission spectra for = 4 plasma at weak coupling, = 4 plasma at strong coupling, and QCD at weak coupling reveals several systematic trends which we discuss. We also evaluate the electric conductivity of = 4 plasma in the strong coupling limit, and to leading-log order at weak coupling. Current-current spectral functions in the strongly coupled theory exhibit hydrodynamic peaks at small frequency, but otherwise show no structure which could be interpreted as well-defined thermal resonances in the high-temperature phase.

In this paper, we develop a new method of computing three-point functions in the SU(2) sector of the $$ \mathcal{N}=4 $$ N = 4 super Yang-Mills theory in the semi-classical regime at weak coupling, which closely parallels the strong coupling analysis. The structure threading two disparate regimes is the so-called monodromy relation, an identity connecting the three-point functions with and without the insertion of the monodromy matrix. We shall show that this relation can be put to use directly for the semi-classical regime, where the dynamics is governed by the classical Landau-Lifshitz sigma model. Specifically, it reduces the problem to a set of functional equations, which can be solved once the analyticity in the spectral parameter space is specified. To determine the analyticity, we develop a new universal logic applicable at both weak and strong couplings. As a result, compact semi-classical formulas are obtained for a general class of three-point functions at weak coupling including the ones whose semi-classical behaviors were not known before. In addition, the new analyticity argument applied to the strong coupling analysis leads to a modification of the integration contour, producing the results consistent with the recent hexagon bootstrap approach. This modification also makes the Frolov-Tseytlin limit perfectly agree with the weak coupling form.

Blockchain has become a promising technology in distributed systems in recent years, but scalability remains a major problem. The traditional approach to scalability, namely sharding, does not solve the problem easily because the process of interleaving blocks stored in different shards to create a unified master ledger introduces overhead. This paper examines two techniques for interleaving the shards of permissioned blockchains, which we refer to as strong temporal coupling and weak temporal coupling. We implement these techniques in a prototype system with a Bitcoin-like transaction structure, using the EPaxos consensus protocol for transaction ordering. Our experimental results show that strong coupling can achieve lower latency as compared to weak coupling but same level of peak throughput. However, strong coupling requires all shards to grow at the same rate, and cannot tolerate any shard failure. In contrast, the higher latency of weak coupling is because of the consensus strategy it uses to order the blocks. However, if shard failure occurs, weak coupling can still make progress without stalling the whole system.

The aim of this paper is to compare strong and weak coupling of the PEEC and MoM method applied to the modeling of magnetoharmonic problem, and to generalize the weak coupling approach. MoM and PEEC are dedicated to the modeling of specific parts of the overall device. As an example of validation, we have chosen the modeling of a simple transformer. Resolutions of several weak couplings are compared to the strong coupling approach. A new strategy of weak coupling is proposed to improve the time of resolution.

In the present paper, a strong coupling and two weak coupling approaches are compared to estimate the aeroelastic stability of a simple sealing system. This test configuration, directly inspired from clarinet modeling [19], combines a valve, represented by a single degree of freedom mechanical element, and an axial acoustic cavity. It displays aeroelastic instabilities due to interactions between mechanical and acoustic modes. The strong coupling (SC) computes directly the eigenmodes of the discrete problem and it is used as the reference solution. The numerical solver is based on low-dissipation and low-dispersion schemes combined with a selective filter. The first weak coupling approach presented here is named the flutter-like weak coupling (FWC), and it is derived from a blade flutter methodology employed in the industry. The second weak coupling method is called the resonator weak coupling (RWC), and it uses a coupling between the mechanical and the acoustic modes. The FWC fails to provide the stability of the present test configuration, whereas the RWC gives better results. However, the assumption made at the junction between the valve and the cavity is a critical issue for the RWC. The number of acoustic modes considered in this model can also impact the results.

Many-body instabilities of the half-filled honeycomb bilayer are studied using weak-coupling renormalization group (RG) as well as strong-coupling expansion. For spinless fermions and assuming parabolic degeneracy, there are four independent four-fermion contact couplings. While the dominant instability depends on the microscopic values of the couplings, the broken symmetry state is typically a gapped insulator with either broken inversion symmetry or broken time-reversal symmetry, with a quantized anomalous Hall effect. Under certain conditions, the dominant instability may appear in the particle-particle (pairing) channel. For some nongeneric fine-tuned initial conditions, weak-coupling RG trajectories flow into the noninteracting fixed point, although generally we find runaway flows which we associate with ordering tendencies. Additionally, a tight-binding model with nearest-neighbor hopping and nearest-neighbor repulsion is studied in weak and strong couplings and in each regime a gapped phase with inversion symmetry breaking is found. In the strong-coupling limit, the ground-state wave function is constructed for vanishing in-plane hopping but finite interplane hopping, which explicitly displays the broken inversion symmetry and a finite difference between the number of particles on the two layers. Finally, we discuss the spin-1/2 case and use Fierz identities to show that the number of independent four-fermion contact couplings is 9. The corresponding RG equations in the spin-1/2 case are also presented, and used to show that, just as in strong coupling, the most dominant weak-coupling instability of the repulsive Hubbard model (at half filling) is an antiferromagnet.

We find half-BPS vortex solitons, at both weak and strong coupling, in the N=6 supersymmetric mass deformation of ABJM theory with U(N) x U(N) gauge symmetry and Chern-Simons level k. The strong coupling gravity dual is obtained by performing a Z_k quotient of the N=8 supersymmetric eleven dimensional supergravity background of Lin, Lunin and Maldacena corresponding to the mass deformed M2-brane theory. At weak coupling, the BPS vortices preserving six supersymmetries are found in the Higgs vacuum of the theory where the gauge symmetry is broken to U(1) x U(1). The classical vortex solitons break a colour-flavour locked global symmetry resulting in non-Abelian internal orientational moduli and a CP^1 moduli space of solutions. At strong coupling and large k, upon reduction to type IIA strings, the vortex moduli space and its action are computed by a probe D0-brane in the dual geometry. The mass of the D0-brane matches the classical vortex mass. However, the gravity picture exhibits a six dimensional moduli space of solutions, a section of which can be identified as the CP^1 we find classically, along with a Dirac monopole connection of strength k. It is likely that the extra four dimensions in the moduli space are an artifact of the strong coupling limit and of the supergravity approximation.

In this work, we use the first-principles calculation method to theoretically study the strong and weak coupling between the layer-dependent MoS2 and electromagnetic waves. Through the calculation of the electronic structure and the analysis and fitting of Van Hove singularity (VHS), the differences between the strong coupling and weak coupling mechanisms are discussed. The exponential law of electronic structure parameters with the number of layers is explained. Finally, combined with cavity quantum electrodynamics (QED), it is revealed that the physical mechanism of strong coupling and weak coupling is related to the transition dipole moment. Strong coupling is dominated by inter-band transitions and weak coupling is dominated by in-band transitions.