Dissipation Strength Research Articles

Heat, particle, and chiral currents in a boundary driven bosonic ladder in the presence of a gauge field

Quantum systems can undergo phase transitions and show distinct features in different phases. The corresponding transport properties can also vary significantly due to the underlying quantum phase. We investigate the transport behaviour of a two-legged bosonic ladder in a uniform gauge field, which is known to have a Meissner-like phase and a vortex phase in the absence of dissipation. The ladder is coupled to bosonic baths at different temperatures, and we study it using the non-equilibrium Green's function method. In particular, we show the presence of a chiral current and how it is affected by the temperature bias and the dissipation strength. We also demonstrate that the opening of a gap between the lower and upper energy band results in the possibility of tuning heat and particle transport through the ladder. We show that for system parameters for which the ground state is in a vortex phase, the system is more sensitive to external perturbations.

Quasi-static cyclic performance of RC exterior beam-column joint assemblages strengthened with geosynthetic materials

The beam-column joints are the most critical and vulnerable part of the RC framed structures when subjected to earthquake load. The objective of the present study is to investigate the cyclic behaviour of seismic and non-seismic exterior reinforced concrete (RC) beam-column joints strengthened with innovative polymeric based geosynthetic materials. Two variants of geosynthetic material named geogrid and geotextile were used for strengthening the beam-column joints in the experimental program. In this strengthening protocol, two different types of strengthening patterns were used in which one was horizontal U-shaped pattern, and the other one was the diagonal cross (X-shaped) pattern. All the beam-column specimens were tested under the quasi-static cyclic loading with controlled amplitude to explore the cyclic performance on the parameters such as failure modes, hysteresis loops, load-deformation envelope curves, ductility, energy dissipation capacity, stiffness and strength degradation behaviour, pinching width ratio, damage index and joint distortion. The test results showed that the adopted strengthening schemes with geotextile and geogrid materials could successfully alter the failure of beam-column joints from shear to flexural and improved the ductile behaviour of the strengthened specimens. The load-carrying capacity and ductility-factor of the geosynthetic strengthened specimens significantly increased up to 48.4% and 37.8%, respectively when compared to the non-seismic control specimen, and it was highest in geogrid strengthened BCJs, especially in diagonal X-shape bonded specimen. The significant increment of energy dissipation capacity was also observed as 2.08 to 3.73 times for the strengthened specimens. Furthermore, the post-elastic performance and the joint shear strength of strengthened RC beam-column joints was also improved in comparison to the non-seismic control specimen. In addition, an analytical study was carried out to predict the shear strength contributions of externally bonded strengthening materials in the RC beam-column joint, which was compared with experimental findings. A good agreement was observed between the analytical and experimental results. Hence, the experimental and analytical study of the strengthened beam-column joints using geotextile and geogrid have confirmed that the appropriate bonding of these materials to the concrete can improve the seismic performance of the non-seismic exterior RC beam-column joints.

Entanglement and quantum discord in optically coupled coherent Ising machines

We present analytical and numerical simulation results for squeezing, entanglement, and quantum discord in a dissipatively coupled coherent Ising machine (CIM). Both analytical solutions and numerical simulation results, which are obtained with positive-$P$, truncated-Wigner, and truncated-Husimi representations for the density operator, predict the presence of entanglement and quantum discord, below and above the threshold of CIM. The entanglement criteria and quantum discord are evaluated as a function of the dissipative coupling strength relative to the background loss. For coupled two DOPOs, while entanglement disappears as the background loss exceeds the Ising coupling strength, the quantum discord remains finite even with a large linear loss. For one-dimensional lattice of DOPOs, while entanglement disappears for DOPO pair with large distance, quantum discord remains finite.

Experimental study on the seismic behavior of prefabricated L-shaped concrete-filled steel tube with rectangular multi-cell columns under different lateral loading directions

Prefabricated residential buildings are becoming the focus of the construction industry. Simultaneously, in order to improve the seismic behavior of traditional RC special-shaped columns, a prefabricated special-shaped concrete-filled steel tube with rectangular multi-cell (S-CFST-R) column was proposed for residential systems. The seismic test of prefabricated L-shaped concrete-filled steel tube with rectangular multi-cell (L-CFST-R) columns was conducted in this study. Three full-scale L-shaped specimens with high practical guidance were designed which were based on the common parameters of residential buildings. A quasi-static test method under a low cycle load was used to simulate the earthquake action. Taking different loading directions (0°, + 45°, and + 135°) as the main research factors, the failure state, bearing capacity, hysteretic behavior, ductility, energy dissipation capacity, strength degradation, stiffness degradation, and strain change of each specimen were studied and analyzed. Moreover, a finite element model was developed to simulate L-CFST-R columns at different loading directions, and the simulation results agreed well with the experimental results. The influence of more loading directions on the ultimate bearing capacity and skeleton curve is analyzed comprehensively. The results indicated that multi-cell special-shaped steel tubes had a strong restraining effect on the core concrete, so the L-CFST-R columns under different lateral loading directions exhibited favorable seismic behavior, which is suitable for prefabricated residential buildings.

Theoretical methods to treat a single dissipative bosonic mode coupled globally to an interacting many-body system

We present two approaches capable of describing the dynamics of an interacting many body system on a lattice coupled globally to a dissipative bosonic mode. Physical realizations are for example ultracold atom gases in optical lattice coupled to a photonic mode of an optical cavity or electronic gases in solids coupled to THz cavity fields. The first approach, applicable for large dissipation strengths and any system size, is a variant of the many-body adiabatic elimination method for investigating the long time dynamics of the system. The second method extends the time-dependent matrix product techniques to capture the global coupling of the interacting particles to the bosonic mode and its open nature. It gives numerically exact results for small to intermediate system sizes. As a benchmark for our methods we perform the full quantum evolution of a Bose-Hubbard chain coupled to a cavity mode. We show that important deviations from the mean-field behavior occur when considering the full atoms cavity coupling [1].

Violation of thermodynamics uncertainty relations in a periodically driven work-to-work converter from weak to strong dissipation

We study a model of isothermal steady-state work-to-work converter, where a single quantum two-level system (TLS) driven by time-dependent periodic external fields acts as the working medium and is permanently put in contact with a thermal reservoir at fixed temperature $T$. By combining Short-Iterative Lanczos (SIL) method and analytic approaches, we study the converter performance in the linear response regime and in a wide range of driving frequencies, from weak to strong dissipation. We show that for our ideal quantum machine several parameter ranges exist where a violation of Thermodynamics Uncertainty Relations (TUR) occurs. We find the violation to depend on the driving frequency and on the dissipation strength, and we trace it back to the degree of coherence of the quantum converter. We eventually discuss the influence of other possible sources of violation, such as non-Markovian effects during the converter dynamics.

Spectral transitions and universal steady states in random Kraus maps and circuits

The study of dissipation and decoherence in generic open quantum systems recently led to the investigation of spectral and steady-state properties of random Lindbladian dynamics. A natural question is then how realistic and universal those properties are. Here, we address these issues by considering a different description of dissipative quantum systems, namely, the discrete-time Kraus map representation of completely positive quantum dynamics. Through random matrix theory (RMT) techniques and numerical exact diagonalization, we study random Kraus maps, allowing for a varying dissipation strength, and their local circuit counterpart. We find the spectrum of the random Kraus map to be either an annulus or a disk inside the unit circle in the complex plane, with a transition between the two cases taking place at a critical value of dissipation strength. The eigenvalue distribution and the spectral transition are well described by a simplified RMT model that we can solve exactly in the thermodynamic limit, by means of non-Hermitian RMT and quaternionic free probability. The steady state, on the contrary, is not affected by the spectral transition. It has, however, a perturbative crossover regime at small dissipation, inside which the steady state is characterized by uncorrelated eigenvalues. At large dissipation (or for any dissipation for a large-enough system), the steady state is well described by a random Wishart matrix. The steady-state properties thus coincide with those already observed for random Lindbladian dynamics, indicating their universality. Quite remarkably, the statistical properties of the local Kraus circuit are qualitatively the same as those of the nonlocal Kraus map, indicating that the latter, which is more tractable, already captures the realistic and universal physical properties of generic open quantum systems.

Comparison of density of states and scattering parameters in coaxial photonic crystals: Theory and experiment

We present an analytical and experimental study of the scattering parameters in a one dimensional (1D) symmetric photonic crystal and their relation to the density of states (DOS). The 1D photonic crystal is constituted by $N$ alternating wires and loops that are either inserted horizontally or attached vertically between the source and load on a transmission line. The complete knowledge of the scattering matrix coefficients (${S}_{ij}$) allows us to access the DOS and eigenvalues of the finite periodic structure as well as the DOS and dispersion curves of an infinite periodic system. We show the usefulness of the transmission and reflection delay times and highlight their similarities and differences with respect to the DOS, in particular as a function of the absorption strength in the system. For both horizontal and vertical geometries, we show analytically that in a lossless structure, the DOS is proportional to the Friedel phase, namely the derivative of the argument of the determinant of the scattering matrix S. For a low loss system, this proportionality remains still valid with a good approximation and can be used as a practical tool to derive the DOS and therefore the dispersion curves from experimental data. Also, the absorption can be accurately extracted from the measurement of the modulus of the determinant of $S$. However, for increasing strength of dissipation, we show how and why these relationships cease to be valid. Still, the transmission delay time can remain an efficient tool to derive DOS even at relatively high dissipation strength. Additionally, we show that in the vertical geometry the transmission and reflection delay times exhibit negative delta peaks which are related directly to the eigenmodes of the finite system with different boundary conditions on its extremities. Our theoretical results are obtained by means of the Green's function approach, whereas the experimental demonstrations are performed using standard coaxial cables in the radio-frequency domain.

ON OSCILLATIONS DESCRIBING A GENERALIZED DIFFERENTIAL RELAY EQUATION

The motion of an oscillatory system with one degree of freedom, described by the generalized Rayleigh differential equation, is considered. The generalization is achieved by replacing the cubic term, which expresses the dissipative strength of the equation of motion, by a power term with an arbitrary positive exponent. To study the oscillatory process involved the method of energy balance. Using it, an approximate differential equation of the envelope of the graph of the oscillatory process is compiled and its analytical solution is constructed from which it follows that quasilinear frictional self-oscillations are possible only when the exponent is greater than unity. The value of the amplitude of the self-oscillations in the steady state also depends on the value of the indicator. A compact formula for calculating this amplitude is derived. In the general case, the calculation involves the use of a gamma function table. In the case when the exponent is three, the amplitude turned out to be the same as in the asymptotic solution of the Rayleigh equation that Stoker constructed. The amplitude is independent of the initial conditions. Self-oscillations are impossible if the exponent is less than or equal to unity, since depending on the initial deviation of the system, oscillations either sway (instability of the movement is manifested) or the range decreases to zero with a limited number of cycles, which is usually observed with free oscillations of the oscillator with dry friction. These properties of the oscillatory system are also confirmed by numerical computer integration of the differential equation of motion for specific initial data. In the Maple environment, the oscillator trajectories are constructed for various values of the nonlinearity index in the expression of the viscous resistance force and a corresponding comparative analysis is carried out, which confirms the adequacy of approximate analytical solutions.

Seismic performance of bolted beam-to-column connection with rib-stiffened splicing plate

A bolted beam-to-column connection with rib-stiffened splicing plates is presented to facilitate on-site assembly and enhance the stiffness of joints. The joints consist of three modules and are assembled using bolts on site. Cyclic tests and a finite element analysis (FEA) are performed on seven full-scale joints. The influence of the trapezoidal stiffener's size, end-plate connection type, and the number of bolts on the seismic performance of the joints is investigated. The seismic performance of the bolted joints is compared with that of a welded joint. The failure mode, hysteretic curve, energy dissipation capacity, ductility, rotation capacity, bolt tension, friction, strength, and stiffness of the joints are determined via the tests and FEA. The trapezoidal stiffener significantly improves the bearing capacity, stiffness, and energy-dissipation capacity of the joints, making the plastic hinge occur on the beam flange outside the splicing zone. It is preferable to move the web bolts to the beam flange for improved seismic performance. The bolts on the four corners of the column flange have little effect on the seismic performance; thus, the bolts can be eliminated and the flange can be substituted by four small plates to reduce cost. This reasonable design could prevent the slipping of the joint during small-magnitude earthquakes, facilitate energy dissipation via slip during medium-magnitude earthquakes, and facilitate energy dissipation via the slip and plastic deformation of the beams during large-magnitude earthquakes. The formula for the ultimate load is presented, and the corresponding calculation results agree well with the test results.

Symmetry of a Square-Wave Modulated Two-Level System**Supported by the National Natural Science Foundation of China (Grant Nos. 11674285 and 11834005) and the National Key Research and Development Program of China (Grant No. 2017YFA0303002).

We study a non-Hermitian two-level system with square-wave modulated dissipation and coupling. Based on the Floquet theory, we achieve an effective Hamiltonian from which the boundaries of the phase diagram are captured exactly. Two kinds of symmetry broken phases are found, whose effective Hamiltonians differ by a constant ω/2. For the time-periodic dissipation, a vanishingly small dissipation strength can lead to the symmetry breaking in the (2k – 1)-photon resonance (Δ = (2k – 1) ω), with k = 1,2,3… It is worth noting that such a phenomenon can also happen in 2k-photon resonance (Δ = 2kΔ), as long as the dissipation strengths or the driving times are imbalanced, namely γ0 ≠ – γ1 or T0 ≠ T1. For the time-periodic coupling, the weak dissipation induced symmetry breaking occurs at Δeff = kω, where Δeff = (Δ0T0 + Δ1T1)/T. In the high frequency limit, the phase boundary is given by a simple relation γeff = ±Δeff.

Spectral and steady-state properties of random Liouvillians

We study generic open quantum systems with Markovian dissipation, focusing on a class of stochastic Liouvillian operators of Lindblad form with independent random dissipation channels (jump operators) and a random Hamiltonian. We establish that the global spectral features, the spectral gap, and the steady-state properties follow three different regimes as a function of the dissipation strength, whose boundaries depend on the particular quantity. Within each regime, we determine the scaling exponents with the dissipation strength and system size. We find that, for two or more dissipation channels, the spectral gap increases with the system size. The spectral distribution of the steady state is Poissonian at low dissipation strength and conforms to that of a random matrix once the dissipation is sufficiently strong. Our results can help to understand the long-time dynamics and steady-state properties of generic dissipative systems.

Simulation of open-quantum-system dynamics using the quantum Zeno effect

We suggest a quantum simulator that allows to study the role of memory effects in the dynamics of open quantum systems. Our proposal is based on a bipartite quantum system consisting, for simplicity, of a harmonic oscillator and a few-level system; it exploits the formal analogy between dissipation and quantum measurements. The interaction between the subsystems gives rise to quantum Zeno dynamics, and the dissipation strength experienced by the harmonic oscillator can be tuned by changing the parameters of the measurement, i.e., the interaction with the few-level system. Extension of the proposal to anharmonic systems is straightforward.

Global regularity of 2D tropical climate model with zero thermal diffusion

AbstractThis article studies the global regularity problem of the two‐dimensional zero thermal diffusion tropical climate model with fractional dissipation, given by in the barotropic mode equation and by in the first baroclinic mode of the vector velocity equation. More precisely, we show that the global regularity result holds true as long as with . In addition, with no dissipation from both the temperature and the first baroclinic mode of the vector velocity, we also establish the global regularity result with the dissipation strength at the logarithmically supercritical level. Finally, our arguments can be extended to obtain the corresponding global regularity results of the higher dimensional cases.

Seismic performance of composite joints between prefabricated steel-reinforced concrete columns and steel beams: experimental study

The joint between beam and column is the crucial zone, which makes the study of seismic performance of fabricated frame structures difficult and challenging. Reliable connection of prefabricated steel-reinforced concrete (SRC) columns with steel beams by a simple and effective dry connection method is a very important technical problem. In view of this, a new type of modular prefabricated SRC column-steel beam composite joint (MPCJ) was developed in this study. Further, the quasi-static test was carried out on three different types of beam-column joints (i.e. bolted-welded hybrid connection, welding connection, and bolted connection), and the failure characteristics, hysteretic behaviour, strain law, ductility, energy dissipation capacity, strength, and stiffness degradation of the new MPCJ under low-cycle reciprocating loads were recorded and analyzed. The results showed that the failure mode of three MPCJ specimens was bending failure at the end of the beam; the MPCJs exhibited stable hysteretic curves, strength deterioration, and stiffness degradation; the ductility coefficients and the equivalent viscous damping coefficients of the three specimens were found to be greater than 4 and 0.2, respectively, which meet the requirements of seismic performance limits. In summary, the new MPCJ has the advantages including large bearing capacity, high construction efficiency, energy saving, and environmental protection. It has important theoretical and practical value for future in-depth study of assembled SRC composite frame structure.

Transition between dissipatively stabilized helical states

We analyze a $XXZ$ spin-1/2 chain which is driven dissipatively at its boundaries. The dissipative driving is modelled by Lindblad jump operators which only act on both boundary spins. In the limit of large dissipation, we find that the boundary spins are pinned to a certain value and at special values of the interaction anisotropy, the steady states are formed by a rank-2 mixture of helical states with opposite winding numbers. Contrarily to previous stabilization of topological states, these helical states are not protected by a gap in the spectrum of the Lindbladian. By changing the anisotropy, the transition between these steady states takes place via mixed states of higher rank. In particular, crossing the value of zero anisotropy a totally mixed state is found as the steady state. The transition between the different winding numbers via mixed states can be seen in the light of the transitions between different topological states in dissipatively driven systems. The results are obtained developing a perturbation theory in the inverse dissipative coupling strength and using the numerical exact diagonalization and matrix product state methods.

Experimental study of seismic performance of full-scale basalt FRP-recycled aggregate concrete-steel tubular columns

Abstract Hybrid fiber-reinforced polymer (FRP)-concrete-steel double-skin tubular columns (DSTCs) have received extensive attention in the research community over the past decade. Generally, a DSTC consists of an inner steel tube and an outer FRP tube, with the space between them filled with natural aggregate concrete (NAC). This paper studied a new form of hybrid FRP-recycled aggregate concrete (RAC)-steel tubular column (FRSTC) in which the outer FRP tube was made of environmental-friendly basalt fibers and the concrete was made of recycled coarse aggregates (RCAs). Quasi-static tests of five full-scale basalt FRSTCs were conducted to gain an improved understanding of the behavior of FRSTCs, and to enable further application potentiality of FRSTCs in earthquake-prone areas. Three key column parameters, including RCA replacement percentages, axial load ratios, and steel reinforcement ratios were carefully designed to clarify their influence on the performance of FRSTCs under combined axial compression and cyclic lateral loading. The test results, including the hysteretic loops, skeleton curves, curvature and strain distributions, ductility characterization, energy dissipation capacity, stiffness and strength degradation, and cumulative damage, are presented and discussed. The experimental results show that the RCA replacement percentage has little impact on the seismic performance of FRSTCs, while the effect of the axial load ratio is significant. The bearing capacity and energy dissipation of FRSTCs can be superior to those of DSTCs with NAC.

Phase transition and emergence of active temperature in an active Brownian system in underdamped background

We explore the role of inertia in the properties of active Brownian particles (ABPs) immersed in an underdamped background in two dimensions using Langevin dynamics computer simulation. Similar to an equilibrium two-dimensional passive interacting particle system, the system of ABPs transits from a liquid phase to a solid phase with the change in the coupling parameter, which is the ratio of interaction potential energy and thermal energy of the background solvent. Important qualitative and quantitative differences are found in the liquid-solid phase transition with increasing strength of activity as compared to those found in the conventional overdamped background limit. In the underdamped background, inherent activity is found to lead to a temperature, called the active temperature and defined by average velocity fluctuations of the ABPs, that is different from the fixed background solvent temperature. A new scaling law for active temperature as a function of activity strength is found near the liquid-solid boundary. Active temperature, which behaves similar to the thermodynamic equilibrium temperature, is also found to depend upon the interaction strength between the active particles and the strength of the background dissipation. With an increase in background dissipation, the difference between active temperature and the background solvent temperature decreases and the difference is found to eventually vanish in the overdamped limit, demonstrating the correctness of the calculation.

Effects of isospin and dissipation coefficient of the K coordinate in simulation of fission dynamics of excited compound nuclei

A stochastic approach based on four-dimensional (4D) dynamical model has been used to simulate the fission process of the excited compound nuclei [Formula: see text]Fr, [Formula: see text]Fr and [Formula: see text]Fr produced in fusion reactions. Effects of isospin and dissipation coefficient of the [Formula: see text] coordinate, [Formula: see text], on estimation of the evaporation residue (ER) cross-section, the prescission neutron multiplicity, the variance of the mass and energy distributions of fission fragments and the anisotropy of fission fragments angular distribution have been investigated for the excited compound nuclei [Formula: see text]Fr, [Formula: see text]Fr and [Formula: see text]Fr. Three collective shape coordinates [Formula: see text] plus the projection of total spin of the compound nucleus to the symmetry axis, [Formula: see text], were considered in the 4D dynamical model. In the 4D dynamical model, the magnitude of the dissipation coefficient of [Formula: see text], [Formula: see text], was considered as a free parameter and its magnitude inferred by fitting measured data on the ER cross-section. Results of the extracted dissipation coefficients of [Formula: see text] for different isotopes of Fr were shown that the magnitude of the dissipation coefficient of [Formula: see text] increases with decreasing isospin of fissioning compound nucleus. It was also shown that the prescission neutron multiplicity and the anisotropy of fission fragments angular distribution increase with increasing isospin whereas the variance of the mass and energy distributions of fission fragments decrease with increasing isospin of fissioning compound nucleus. Furthermore, it was shown that the calculated values of prescission neutron multiplicity and the variance of the mass distribution of fission fragments for the excited compound nuclei [Formula: see text]Fr, [Formula: see text]Fr and [Formula: see text]Fr decrease with the dissipation strength of [Formula: see text], whereas the variance of the energy distribution of fission fragments and the anisotropy of fission fragments angular distribution increase with the dissipation strength of [Formula: see text].

EXPERIMENTAL STUDY ON SEISMIC PERFORMANCE OF PEC COLUMN-SPECIAL SHAPED STEEL BEAM INNER-FRAME JOINTS

To study the failure pattern and seismic performance of PEC column (partially encased concrete composite column)-steel beam inner-frame joints, three PEC column-steel beam inner-frame joints and one steel frame beam-to-column inner-frame joint were tested under low-cycle reversed loading. Several parameters including the failure mode, hysteretic behavior, load carrying capacity, ductility performance, degradation of strength and stiffness and mechanical mechanism of the inner joints were analyzed. The effect of axial load ratio and beam section variation on the seismic performance of the joints were studied. Experimental results indicated that the hysteresis curve of PEC column-steel beam inner-frame joints was of a spindle shape, and these joints had similar mechanical characteristics to steel frame joints. The initial stiffness and capacity increased about 40% and 31.1% respectively, while steel column filled with concrete. The specimens still had good ductility performance and energy dissipation ability. As the test axial load ratio increased from 0.25 to 0.35, the bearing capacity and the energy dissipation capacity of the specimens increased while the ductility performance decreased. The failure feature of specimens are the bending of beams and no obvious change in the degree of damage. The capacity and ductility performance of specimens were improved when the beam section on one side of the column were changed. The energy dissipation capacity, strength and stiffness degradation have no noticeable changes due to the variation in the beam section, but the failure patterns of the inner-frame joints were shearing diagonal compression in joint zones. The main reason for the failure patterns was the increase in the input shear force in the joint with the variation of the beam height on one side of column. The variable section beam joints designed according to the conventional joints cannot meet the seismic design requirements of the strong node weak member, and it should be taken into serious account in engineering design.