arXiv subjects

Wen-Li Yang

Publications and source records attributed to Wen-Li Yang.

At least 19 recordsLinked to original sources

arXiv2026

Explicit Boundary-Entropy Deficits in the XX Spin Chain with arbitrary boundary fields

The exact thermodynamics of the XX spin-1/2 chain with arbitrary Hermitian boundary fields is constructed via fusion techniques. The rigorous result shows that (1) each end with a nonzero transverse field contributes $+\frac12T\ln2$ to the low-temperature free energy, whereas strictly diagonal and free ends contribute no such linear term; (2) each nondiagonal end has a characteristic temperature $T_B$, which scales as $T_B\propto h_\perp^2/J$ in the weak-field regime. For $T\ll\min\{J,T_B\}$, the boundary entropy approaches a deficit of $\frac12\ln2$ relative to a diagonal end. As the transverse field tends to zero, the boundary crossover scale vanishes and the low-temperature expansion becomes nonuniform. The present result provides a clear benchmark not only for the boundary thermodynamics of open boundary quantum integrable systems, but also for dot defects in quantum critical systems.

math-ph↗

arXiv2026

Ground state and excitations of the $C_2^{(1)}$ spin chain with non-diagonal boundaries

Understanding boundary effects in higher-rank integrable quantum spin chains requires connecting exact spectral relations with the root configurations underlying their energies and excitations. With non-diagonal boundaries, determining these configurations remains challenging even when an exact spectral solution is available, hindering the direct extraction of thermodynamic properties. We address this problem for the rational $C_2^{(1)}$ chain by combining DMRG in the tensor-network framework with the quantum inverse scattering method. The numerically determined zeros of the fundamental and fused transfer-matrix eigenvalues reveal three bulk-string distributions, labeled by $x$, $y$, and $w$, together with boundary strings and additional roots. Substituting these configurations into the operator identities relating the two transfer matrices yields the ground-state energy and the surface energy in the thermodynamic limit under non-diagonal boundary conditions. The analytical surface energy agrees with the numerical results up to $O(\tfrac1N)$ corrections. From the regularity conditions of the operator identities, we derive a boundary-string selection rule and numerically identify allowed configurations beyond the ground state. For excitations preserving the boundary-string configuration, we identify three elementary hole excitations, $X$, $Y$, and $W$, in the $x$-, $y$-, and $w$-string distributions, respectively, and derive their energies. Based on the symmetry of the zero roots, we also present a bulk-excitation selection rule governing the allowed combinations of these elementary excitations in physical eigenstates. The framework developed here can therefore be used to systematically analyze boundary effects, bulk excitations, and related physical properties in other high-rank integrable quantum models with non-diagonal boundary conditions.

nlin.SI↗

arXiv2026

An elliptic generalization of the $D^{(2)}_{2}$ Spin chain

An integrable elliptic generalization of the closed $D^{(2)}_2$ quantum spin chain is constructed. Taking the trigonometric limit, we have shown that the corresponding R-matrix reduces to that of the $D^{(2)}_2$ one, up to a similarity transformation. Basing on the very fact of the factorization for the R-matrix and the corresponding transfer matrix which indeed ensures the integrability of the model, we give the exact solution of the model which can be expressed in terms of a homogeneous T-Q relation.

math-ph↗

arXiv2026

Spectral Oscillations and Temporal Meandering of Dissipative Solitons in a Moving Intracavity Phase Potential

Dissipative solitons (DSs) provide a prototypical platform for studying nonequilibrium dynamics governed by the interplay between nonlinearity, dissipation, and external driving. In particular, subjected to external potentials, DSs exhibit a rich variety of nonlinear dynamical behaviors. This work investigates DS dynamics in a moving intracavity potential generated by phase modulation whose frequency is detuned from an integer multiple of the cavity repetition rate. Modulation detuning introduces a timescale mismatch between the DS and the moving potential, leading to two distinct dynamical regimes. At large detuning, the DS cannot continuously track the moving potential and exhibits persistent spectral oscillations and temporal meandering, whereas at sufficiently small detuning it enters a synchronized locking state. Furthermore, both the oscillation period and amplitude can be tuned via the modulation detuning and modulation depth. These results reveal how asynchronous driving reshapes DS dynamics and establish a route for controlling their dynamical response in nonlinear optical cavities.

nlin.PS↗

arXiv2026

Photoinduced Odd- and Mixed-Parity Magnetism in Collinear Antiferromagnets

Altermagnetism, characterized by compensated collinear magnetic moments and even-parity momentum-dependent spin splitting, has emerged as a distinct form of magnetic order. However, realizing odd- and mixed-parity magnetism in fully compensated collinear magnets remains challenging. Here, we demonstrate light-induced odd- and mixed-parity magnetism in conventional collinear antiferromagnets. Combining Floquet theory with first-principles calculations, we show that circularly polarized light (CPL) induces odd-parity $f$-wave spin splitting in monolayer CoS and CoSe, whereas elliptically polarized light (EPL) induces $p$-wave spin splitting. Uniaxial strain combined with CPL offers an alternative route to the $p$-wave state. Furthermore, combining an electric field with CPL or EPL generates mixed-parity spin splitting. Light-induced breaking of $\mathcal{PT}$ symmetry, together with spin-orbit coupling, gives rise to a finite anomalous Hall response. Our findings establish a versatile approach to engineering spin splitting and controlling electronic and magnetic properties in compensated antiferromagnets.

cond-mat.mtrl-sci↗

arXiv2026

Anomaly fluctuation theorem for quantum coherence dynamics

Quantum coherence is a central resource in quantum information science, yet general frameworks and constraints governing its dynamics remain limited. Although quantum coherence lacks a general monotonicity law, we establish an exact integral fluctuation theorem (FT) for coherence dynamics, formulated in terms of Kirkwood-Dirac (KD) quasiprobability trajectories and valid for arbitrary initial states and dynamics. This integral FT deviates from the standard unit-valued form, and the complex deviation, termed the anomaly, quantifies a weighted overlap between the residual final-state coherence and the coherence generated from the dephased input. The real part of the anomaly yields bounds on coherence change, while its imaginary part constrains the second-order moment of the stochastic coherence change weighted by the imaginary parts of the KD quasiprobabilities. Our results establish general statistical constraints on coherence dynamics, demonstrating the utility and broad applicability of FTs for studying quantum-resource dynamics.

quant-ph↗

arXiv2026

Tensor-Network Analysis of Root Patterns in the XXX Model with Open Boundaries

The string hypothesis of Bethe roots is a cornerstone in the thermodynamic analysis of quantum integrable systems, since it connects root configurations with physical quantities such as the ground-state energy, surface energy and excitation spectra. For integrable models with $U(1)$ symmetry, this connection is well established. When the $U(1)$ symmetry is broken by generic non-diagonal boundary fields, however, the off-diagonal Bethe Ansatz leads to an inhomogeneous $T\text{--}Q$ relation whose Bethe roots have highly nontrivial distributions. This raises two fundamental questions: whether the zero roots and the ODBA Bethe roots still possess regular and classifiable structures in the large-size limit, and whether such structures can be used to extract physical quantities. In this work, we address these two questions for the isotropic Heisenberg spin chain with non-diagonal open boundaries. By combining tensor-network algorithms with Bethe-Ansatz techniques, we determine the zero-root and Bethe-root configurations associated with the $Λ\text{--}θ$ relation and the inhomogeneous Bethe Ansatz equations for large system sizes, up to $N\simeq 60$ and $100$. We find that, despite the absence of $U(1)$ symmetry, the roots exhibit well-organized patterns. The zero roots form bulk strings, boundary strings and additional roots, while the ODBA Bethe roots split into four geometric classes: regular roots, line roots, arc roots and paired-line roots.

math-ph↗

arXiv2026

Higher-order topological insulators in two-dimensional antiferromagnetic and altermagnetic chromium-based group-IV chalcogenides

Based on first-principles calculations combined with theoretical analysis, we identify a family of monolayer chromium-based group-IV chalcogenides as a new class of two-dimensional (2D) magnetic higher-order topological insulators (HOTIs). Specifically, the CrC$X_3$ ($X=$ S, Se, Te) and CrSiS$_3$ monolayers are found to host conventional antiferromagnetic ground states with $\mathcal{PT}$ symmetry, whereas the Janus compounds Cr$_2$C$_2$S$_3$Se$_3$ and Cr$_2$Si$_2$S$_3$Se$_3$ exhibit altermagnetic ground states. We demonstrate that all these monolayer magnetic materials realize 2D HOTI phases, in which the nontrivial topology is protected by lattice $C_3$ rotational symmetry and manifests as zero-dimensional corner states carrying quantized fractional charges. Moreover, upon inclusion of spin-orbit coupling, these systems remain in the HOTI phase and continue to host robust corner-localized states, confirming the stability of their higher-order topological nature. Our results reveal an intrinsic connection between higher-order topology and magnetic order in 2D antiferromagnetic and altermagnetic systems, identifying chromium-based group-IV chalcogenide monolayers as promising platforms for exploring higher-order topological phases and their potential relevance for future topological and spintronic applications.

cond-mat.mtrl-sci↗

arXiv2026

Electric-Field-induced Two-Dimensional Fully Compensated Ferrimagnetism and Emergent Transport Phenomena

The recent discovery of altermagnetism has demonstrated that spin-split electronic band structures can emerge in magnetic systems with zero net magnetization. In contrast, fully compensated ferrimagnetic (fFIM) systems remain far less explored, despite exhibiting similar characteristics such as vanishing magnetization and spin-split bands. Here, based on first-principles calculations combined with theoretical analysis, we demonstrate that monolayer CoS and CoSe can be driven into fFIM states by an external electric field. These materials possess collinear antiferromagnetic ground states with out-of-plane Néel vectors, and their electronic bands are spin degenerate due to $\mathcal{PT}$ symmetry. When an out-of-plane electric field is applied, $\mathcal{PT}$ symmetry is broken, inducing fFIM states with pronounced spin splitting. Moreover, we show that the resulting fFIM states host fully spin-polarized currents, anomalous Hall effects, and magneto-optical Kerr and Faraday effects. Our results establish monolayer CoS and CoSe as promising platforms for electric-field-controlled fFIM states and spintronic applications.

cond-mat.mtrl-sci↗

arXiv2026

Integrable Stochastic Processes Associated with the $D_2$ Algebra

We introduce an integrable stochastic process associated with the $D_2$ quantum group, which can be decomposed into two symmetric simple exclusion processes. We establish the integrability of the model under three types of boundary conditions (periodic, twisted, and open boundaries), and present its exact solution, including the spectrum, eigenstates, and some observables. This integrable model can be generalized to the asymmetric case, decomposing into two asymmetric simple exclusion processes, and its exact solutions are also studied.

math-ph↗

arXiv2025

Optimal energy storage in the Tavis-Cummings quantum battery

The Tavis-Cummings (TC) model, which serves as a natural physical realization of a quantum battery, comprises $N_b$ atoms as battery cells that collectively interact with a shared photon field, functioning as the charger, initially containing $n_0$ photons. In this study, we introduce the invariant subspace method to effectively represent the quantum dynamics of the TC battery. Our findings indicate that in the limiting case of $n_0\!\gg\! N_b$ or $N_b\!\gg\! n_0$, a distinct SU(2) symmetry emerges in the dynamics, thereby ensuring the realization of optimal energy storage. We also establish a negative relationship between the battery-charger entanglement and the energy storage capacity. As a result, we demonstrate that the asymptotically optimal energy storage can be achieved in the scenario where $N_b\!=\!n_0\!\gg\! 1$. Our approach not only enhances our comprehension of the algebraic structure inherent in the TC model but also contributes to the broader theoretical framework of quantum batteries. Furthermore, it provides crucial insights into the relation between energy transfer and quantum correlations.

quant-ph↗

arXiv2025

Exact surface energies and boundary excitations of the Izergin-Korepin model with generic boundary fields

The Izergin-Korepin model is an integrable model with the simplest twisted quantum affine algebra $U_q(A_2^{(2)})$ symmetry. Applying the $t-W$ method, we derive the homogeneous zero roots Bethe ansatz equations and the corresponding zero root patterns of the Izergin-Korepin model with generic integrable boundaries. Based on these results, we analytically compute the surface energies and boundary excitations in different regimes of boundary parameters of the model. It is shown that in some regimes, correlation effect appears between two boundary fields.

math-ph↗

arXiv2025

Exact physical quantities of the $D_2^{(2)}$ spin chain model with generic open boundary conditions

We study the quantum integrable spin chain model associated with the twisted $D_2^{(2)}$ algebra (or simply the $D_2^{(2)}$ model) under generic open boundary conditions. The Hamiltonian of this model can be factorized into the sum of two staggered XXZ spin chains. Applying the $t$-$W$ method, we derive the homogeneous Bethe ansatz equations for the zeros of the transfer matrix eigenvalues and the patterns of the corresponding zeros of the staggered XXZ spin chain with generic integrable boundaries. Based on these results, we analytically compute the surface energies and excitation energies of the $D_2^{(2)}$ model in different regimes of boundary parameters.

math-ph↗

arXiv2025

Exact Spectral Function of One-Dimensional Bose Gases

Exactly solved models provide rigorous understanding of many-body phenomena in strongly correlated systems. In this article, we report a breakthrough in uncovering universal many-body correlated properties of quantum integrable Lieb-Liniger model. We calculate exactly the dynamical correlation functions by computing the form factor through a newly developed method, by which we are capable of calculating all possible "relative excitations" over the ground state or a finite temperature state at a high precision. Consequently, full spectral functions obtained for the model manifests the unique power-law singularity behaviour at the spectral threshold, confirming the validity of nonlinear Luttinger liquid theory. Our method advances the theory of dynamical correlation functions with high precision towards the thermodynamic limit, and is capable of benchmarking experimental observation of such novel correlated properties.

cond-mat.quant-gas↗

arXiv2025

Experimental observation of recurrence and spectral asymmetry of the two-component Akhmediev breathers in a single mode optical fibre

We report the results of experimental studies of recurrent spectral dynamics of the two component Akhmediev breathers (ABs) in a single mode optical fibre. We also provide the theoretical analysis and numerical simulations of the ABs based on the two component Manakov equations that confirm the experimental data. In particular, we observed spectral asymmetry of fundamental ABs and complex spectral evolution of second-order nondegenerate ABs.

physics.optics↗

arXiv2025

One-body dynamical correlation function of Lieb-Liniger model at finite temperature

The dynamical correlated properties of one-dimensional (1D) Bose gases provide profound understanding of novel physics emergent from collective excitations, for instance, the breakdown of off-diagonal long-range order, and the establishment of Tomonaga-Luttinger liquid theory. However, due to the nonperturbative nature of 1D many-body systems, the exact evaluation of correlation functions is notoriously difficult. Here, by means of a form factor approach based on an algebraic Bethe ansatz and numerics, we present a thorough study on the one-body dynamical correlation function (1BDCF) of the Lieb-Liniger model at finite temperature. The influence of thermal fluctuation and interaction on the behavior of 1BDCF has been demonstrated and analyzed from various perspectives, including the spectral distribution, the line shape at fixed momentum, and the corresponding static correlations.

cond-mat.quant-gas↗

arXiv2025

Quantum Charging Advantage from Multipartite Entanglement

Collective quantum batteries (QBs) demonstrate remarkable acceleration in charging dynamics compared to their individual counterparts, underscoring the pivotal contribution of quantum correlations to advanced energy storage paradigms. A fundamental challenge lies in identifying QBs that exhibit genuine quantum advantages derived from multipartite entanglement. In this Letter, based on numerical and analytical evidence, we conjecture a universal bound on the charging rate for fully charging schemes, which is determined by the maximum entanglement depth arising during the charging dynamics. Here, the charging rate quantifies the intrinsic evolution speed of the charging process, appropriately normalized against the quantum speed limit (QSL). We analytically validate this conjecture in three distinct scenarios: (i) fully charging schemes saturating the QSL, (ii) fully parallel charging schemes, and (iii) the SU(2) fully charging schemes. Moreover, we establish a novel lower bound for entanglement depth detection, facilitating numerical verification of our proposed conjecture. By defining the genuine quantum charging advantage as the ratio between entanglement-enhanced charging rates and the maximum achievable non-entangling charging rate, we demonstrate that the charging rate constitutes a robust indicator of genuine quantum advantages.

quant-ph↗

arXiv2024

Exact solution of a quantum integrable system associated with the $G_2$ exceptional Lie algebra

A quantum integrable spin chain model associated with the $G_2$ exceptional Lie algebra is studied. By using the fusion technique, the closed recursive relations among the fused transfer matrices are obtained. These identities allow us to derive the exact energy spectrum and Bethe ansatz equations of the system based on polynomial analysis. The present method provides a unified treatment to investigate the Bethe ansatz solutions for both periodic and non-diagonal open boundary conditions associated with exceptional Lie algebras.

math-ph↗