Frustrated spin-1/2 model with all-antiferromagnetic exchange on Shastry-Sutherland lattice (SSL) has been extensively explored, and in this work we study the quantum phase diagram of isotropic Heisenberg spin-$1/2$ model on the SSL with ferromagnetic exchange interactions along leg, and antiferromagnetic couplings along the diagonal bonds ($J$). Using density matrix renormalization group (DMRG) and exact diagonalization calculations, we identify four distinct ground-state (gs) phases for this frustrated spin-1/2 model: stripe $(\pi ,0)$, stripe $(0,\pi )$, ferromagnetic, and spiral-dimer phases. In the spiral-dimer phase the gs can exhibit dimer formation along the diagonal bonds with or without spins spiral along the $x$ axis or $y$ axis in different parameter regime and these states are connected through crossovers. There is a continuous transition between stripe with a long-range spin-spin correlations and spiral-dimer phase with a short-range correlations. An effective spin parameter is introduced to accurately determine the phase boundaries. Our DMRG results differ significantly from previous Schwinger boson mean-field theory predictions. The spiral phase occurs in a narrow range of the parameter space and shows short-range correlations in the system.

Tidal Love numbers (TLNs) characterize the response of compact objects to external tidal fields and vanish for classical Schwarzschild and Kerr black holes in general relativity. Nonvanishing TLNs therefore provide a potential observational window into beyond-classical physics. In this work, we present a unified and fully analytic study of the TLNs of three representative classes of regular black holes—the Bardeen black hole, the black hole with sub-Planckian curvature, and the black hole arising in asymptotically safe gravity—under scalar, vector, and axial gravitational perturbations. Employing a Green’s function method combined with systematic perturbative expansions, we show that TLNs of regular black holes are generically nonzero and exhibit strong model and mode dependence. In many cases, higher-order corrections develop logarithmic scale dependence, closely resembling renormalization-group running in quantum field theory and revealing a scale-dependent tidal response absent in classical black holes. Our analysis demonstrates that the internal structure of regular black holes, including de Sitter or Minkowski cores and quantum-gravity-inspired modifications, leaves distinct fingerprints in their tidal properties. These results provide a comparative theoretical benchmark for assessing regular black-hole models and establish a basis for future phenomenological and observational studies with gravitational-wave detectors.

Stacking geometry in multilayer graphene (MLG) provides an interesting degree of freedom to engineer its electronic structure near the Fermi level, wherein the linear bands in single layer graphene could retain or evolve into parabolic or flat bands. Using a tight-binding model, we carried out a detailed analytical analysis of the electronic band structures for arbitrarily stacked MLGs. We show that their low-energy band dispersions near the Fermi level may be deduced from its substacks in isolation. The analytical solutions of the momenta with zero eigenvalue for an AA stacking allow us to generalize the results of the zero-energy momenta for arbitrarily stacked MLGs. Moreover, we find that an interplay of parallel and rhombohedral stacking allows for flat band engineering and enhancement in arbitrarily stacked MLG. The existence of enhanced flat bands in our discussed arbitrarily stacked MLGs might offer another interesting platform for exploring the flat band physics and possible flat band properties, like superconductivity, in graphene systems beyond the twisted bilayer graphene and simpler stacking orders.

We examine the complementarity among coherence (visibility), predictability, and entanglement for qubit and qutrit systems subjected to noisy quantum channels. Using the system-path entanglement framework, analytical expressions for all three quantities are derived for two-, three-, and $n$-slit interferometric setups. The study first establishes the validity of the triality relation in ideal conditions and then investigates its behavior under amplitude and phase damping. We find that amplitude damping redistributes coherence and population imbalance without violating complementarity, while phase damping reduces coherence but leaves predictability unchanged. We further extend the study to non-Markovian amplitude damping, where environmental memory effects lead to nonmonotonic evolution and revivals of coherence and entanglement. These results demonstrate that the complementarity relation remains preserved even in open quantum systems, highlighting its robustness against decoherence for both Markovian and non-Markovian open-system dynamics and providing a unified analytical understanding of noisy quantum interferometry in low-dimensional systems.

We model a direct solid-state phase transition through a nucleation-and-growth process in which plates have simple, regular shapes—squares, cubes, or square-faced lamellae—and grow homothetically (self-similarly) until they either reach a randomly assigned maximum size or are stopped by impingement with previously formed plates. The reverse transformation is represented by the preferential disappearance of smaller plates, while larger plates are retained during an incomplete reversion. A subsequent direct transformation therefore produces a modified plate-size distribution—a memory effect that forms the main focus of this study. Building upon an earlier two-dimensional ($2\mathrm{D}$) formulation, we extend the model to cubes ($3\mathrm{D}$) and to lamellar plates ($3{\mathrm{D}}_L$) in order to examine how dimensionality affects transformation memory. We introduce a quantitative descriptor of memory, the size mass ratio and find that memory is robust in all geometries but overall stronger in $2\mathrm{D}$ than in $3\mathrm{D}$ or $3{\mathrm{D}}_L$. We provide growth snapshots, arrest-regrowth cycles, size distributions, and differential scanning calorimetry simulations, and we compute the Shannon size-entropy to quantify configurational diversity. Although motivated by the thermal memory effect in shape-memory alloys, the model more generally identifies a purely geometric mechanism for memory in first-order solid-solid transformations, highlighting the role of dimensionality and geometric blocking in controlling the strength of transformation memory.

The ultrafast nonlinear optical responses of materials are not just theoretical concepts, but they play a significant role in developing modern photonic and optoelectronic devices, including optical time crystals. However, conventional materials often display either weak optical nonlinearities or slow response in the nanosecond timescale, rendering them ineffective for single-shot femtosecond pulse. This limitation can be overcome by leveraging the ultrafast charge transfer that is less than or equal to the pulse width of the laser in a donor-acceptor material pair. However, the low charge-transfer rates limit their effectiveness in high-speed applications. Here, we synthesized titanium carbide MXene-${\mathrm{VS}}_2$ hybrids characterized by strong electronic coupling, resulting in a remarkable enhancement in the ultrafast third-order nonlinear optical responses, enabled by charge transfer in less than the pulse width. For instance, we obtained a third-order nonlinear optical absorption coefficient of $(150\pm 16)\times {10}^{-3}$ cm/GW and a self-focusing (positive) nonlinear refractive index of $(94\pm 9)\times {10}^{-6}{\mathrm{cm}}^2/\mathrm{GW}$ at 800 nm in the femtosecond domain, both exceeding control samples by more than an order of magnitude. These enhancements are attributed to efficient charge transfer within the hybrid structure, supported by first-principles calculations and Bader charge analysis. Our findings have led to the development of an ultrafast optical limiter, featuring an onset threshold as low as $0.60\pm 0.05\mathrm{mJ}/{\mathrm{cm}}^2$, with a differential limiting transmittance of $0.46\pm 0.02$. These parameters are better than or comparable to the known benchmarks for high-speed nonlinear optical applications, demonstrating the potential for advanced photonic and optoelectronic devices.

An incommensurate charge density wave (CDW) is a periodic modulation of charge that breaks translational symmetry incongruently with the underlying lattice. Its low-energy excitations, the phasons, are collective, gapless phase fluctuations. We study a half-filled, four-band ladder model where a shift $\delta =p/q$ between the legs leads to a supercell of $q$ composite cells. The moiré potential narrows minibands near the Fermi level, resulting in additional peaks in the density of states, whose separation is controlled by $\delta$. The inclusion of short-range Coulomb interactions leads to an excitonic incommensurate CDW state. We identify the oscillations in its amplitude with a gapped Higgs collective mode and a lowest-energy Goldstone mode, realized by long-lived neutral phasons whose propagation velocity is governed by the shift $\delta$ and the interleg tunneling amplitude. Our results show that even the slightest interlayer mismatches can strongly modify both charge-ordering patterns and low-energy bosonic excitations in layered materials, and suggest that the enigmatic CDW phase in the quasi-one-dimensional compound ${\mathrm{HfTe}}_3$ is excitonic in nature.