arXiv subjects

Yao-Ting Wang

Publications and source records attributed to Yao-Ting Wang.

13 recordsLinked to original sources

arXiv2026

Temporal Coupled Mode Theory for a Single Floquet-Sheet Resonator

We develop a rigorous Temporal Coupled-Mode Theory (TCMT) specifically tailored for a single Floquet-sheet resonator governed by time-modulated conductivities. By invoking photon-number conservation during frequency conversion, we derive characteristic radiative decay rates and coupling coefficients that account for the frequency ratio between channels. We establish a systematic bridge to the Floquet Transfer Matrix Method (TMM), providing closed-form analytical expressions that map scattering parameters to the Drude-type physics of the sheet. Our model explicitly captures the resonant coupling between the 0th-order propagating channel and the -1st-order surface-mode channel. Validated by COMSOL numerical simulations, the theory remains robust even when intrinsic material loss is incorporated. This framework offers an intuitive pole-expansion representation for designing time-varying photonic interfaces.

physics.optics↗

arXiv2026

Barriers to Discrete Reasoning with Transformers: A Survey Across Depth, Exactness, and Bandwidth

Transformers have become the foundational architecture for a broad spectrum of sequence modeling applications, underpinning state-of-the-art systems in natural language processing, vision, and beyond. However, their theoretical limitations in discrete reasoning tasks, such as arithmetic, logical inference, and algorithmic composition, remain a critical open problem. In this survey, we synthesize recent studies from three theoretical perspectives: circuit complexity, approximation theory, and communication complexity, to clarify the structural and computational barriers that transformers face when performing symbolic computations. By connecting these established theoretical frameworks, we provide an accessible and unified account of why current transformer architectures struggle to implement exact discrete algorithms, even as they excel at pattern matching and interpolation. We review key definitions, seminal results, and illustrative examples, highlighting challenges such as depth constraints, difficulty approximating discontinuities, and bottlenecks in inter-token communication. Finally, we discuss implications for model design and suggest promising directions for overcoming these foundational limitations.

cs.CL↗

arXiv2025

Intrinsic Rashba Spin-Orbit Coupling in Staggered-Gyromagnetic Photonic Crystals

We report the realization of intrinsic Rashba spin-orbit coupling (SOC) in a two-dimensional photonic crystal composed of staggered-gyromagnetic cylinders in a modified honeycomb lattice. The system exhibits a Mexican-hat-like band structure and helical spin textures, which is the major characteristics of Rashba SOC. Through both full-wave simulations and k-p theory, we confirm the emergence of spin-split bands and vortex-like spin textures centered at the Brillouin zone. In addition, under oblique incidence, the Rashba band dispersion gives rise to concurrent negative and a positive refraction. These results establish a platform for exploring intrinsic Rashba photonics and spin-controlled wave transport in periodic systems.

physics.optics↗

arXiv2025

OmniScience: A Domain-Specialized LLM for Scientific Reasoning and Discovery

Large Language Models (LLMs) have demonstrated remarkable potential in advancing scientific knowledge and addressing complex challenges. In this work, we introduce OmniScience, a specialized large reasoning model for general science, developed through three key components: (1) domain adaptive pretraining on a carefully curated corpus of scientific literature, (2) instruction tuning on a specialized dataset to guide the model in following domain-specific tasks, and (3) reasoning-based knowledge distillation through fine-tuning to significantly enhance its ability to generate contextually relevant and logically sound responses. We demonstrate the versatility of OmniScience by developing a battery agent that efficiently ranks molecules as potential electrolyte solvents or additives. Comprehensive evaluations reveal that OmniScience is competitive with state-of-the-art large reasoning models on the GPQA Diamond and domain-specific battery benchmarks, while outperforming all public reasoning and non-reasoning models with similar parameter counts. We further demonstrate via ablation experiments that domain adaptive pretraining and reasoning-based knowledge distillation are critical to attain our performance levels, across benchmarks.

cs.AI↗

arXiv2022

Saturable time-varying mirror based on an ENZ material

We report a switchable time-varying mirror, composed of an ITO-Au stack, which can be efficiently modulated in time with over a ten-fold increase in reflectivity, with a change of 0.6. Upon interacting with the time-varying mirror, the frequency content of a reflected pulse is extended to 31 THz. This originates from the shortening of the response time of the mirror beyond saturation, as confirmed by a time-varying model and by further four-wave mixing experiments. A temporal response unbounded by the pump bandwidth opens new avenues for spectral manipulation from time-varying systems with impact for communication networks, optical switching and computing. We report a switchable time-varying mirror, composed of an ITO-Au bilayer, displaying a ten-fold modulation of reflectivity ($ΔR \approx 0.6$), which saturates for a driving pump intensity $I_{\mathrm{pump}}\approx 100$~GW/cm$^2$. Upon interacting with the saturated time-varying mirror, the frequency content of a reflected pulse is extended up to 31 THz, well beyond the pump spectral content (2.8 THz). We interpret the spectral broadening as a progressive shortening of the mirror rise time from 110 fs to sub 30 fs with increasing pump power, which is confirmed by four-wave mixing experiments and partially captured by a linear time-varying model of the mirror. A temporal response unbounded by the pump bandwidth opens new avenues for spectral manipulation from time-varying systems with impact for communication networks, optical switching and computing.

physics.optics↗

arXiv2022

Surface-Wave Coupling in Double Floquet Sheets Supporting Phased Temporal Wood Anomalies

We investigate symmetry-selective surface-mode excitation in a general periodically time-modulated double-layer system, where the modulation of the two layers has a constant phase difference. By deriving a semi-analytic trans-fer matrix formalism of a Drude-dispersive double-layer structure with periodic time-modulation, we calculate the scattering amplitudes and the corresponding transmission coefficient. Our results show that the phase-difference between the modulation of the two sheets plays an essential role in significantly enhancing and selectively exciting either the even or odd surface mode with high efficiency. We verify our calculations with full-wave time-domain simulations, showing that efficient switching between the surface-wave excitation of the two distinct modal chan-nels can be achieved, even under illumination from a single off-resonant Gaussian pulse, by controlling the phase difference between the two modulations. Our results pave the way towards ultrafast, symmetry-selective mode excitation and switching via temporal modulation.

physics.optics↗

arXiv2020

Designing Hyper-Thin Acoustic Metasurfaces with Membrane Resonators

We design extremely-thin acoustic metasurfaces, providing a versatile platform for the manipulation of reflected pressure fields, that are constructed from mass loads and stretched membranes fixed to a periodic rigid framework. These metasurfaces demonstrate deeply subwavelength control and can have thicknesses an order of magnitude less than those based around Helmholtz resonators. Each sub-unit of the metasurface is resonant at a frequency tuned geometrically, this tunability provides phase control and using a set of finely tuned membrane resonators we create a phase-grating metasurface. This surface is designed to exhibit all-angle negative reflections with the ratio of wavelength, $λ$, to thickness, $h$, of $λ/h\approx 23.1$, and to create a flat mirror using the phase profile of an elliptic reflecting mirror. A further important acoustic application is to sound diffusers and we proceed to design a deeply subwavelength membrane-based meta-diffuser that can be two orders of magnitude thinner than the operating wavelength, i.e. thickness $\approxλ/102$. This paves the way for developing advanced acoustic metasurfaces with applicability to functional acoustic devices in sound-related industries.

physics.app-ph↗

arXiv2020

Wood Anomalies and Surface-Wave Excitation with a Time-Grating

In order to confine waves beyond the diffraction limit, advances in fabrication techniques have enabled subwavelength structuring of matter, achieving near-field control of light and other types of waves. The price is often expensive fabrication needs and the irreversibility of device functionality, as well as the introduction of impurities, a major contributor to losses. In this Letter, we propose temporal inhomogeneities, such as a periodic drive in the electromagnetic properties of a surface which supports guided modes, to circumvent the need for subwavelength fabrication in the coupling of propagating waves to evanescent modes across the light line, achieving the temporal counterpart of the Wood anomaly. We show analytically and numerically how this concept is valid for any material platform and at any frequency, and propose and model a realistic experiment in graphene to couple terahertz radiation to plasmons with unit efficiency, demonstrating that time-modulation of material properties could be a tunable, lower-loss and fast-switchable alternative to the subwavelength structuring of matter for near-field wave control.

physics.app-ph↗

arXiv2019

Acoustic metamaterials with spinning components

Using both multiple scattering theory and effective medium theory, we find that an acoustic metamaterial consisting of an array of spinning cylinders can possess a host of unusual properties including folded bulk and interface-state bands in the subwavelength regime. The folding of the bands has its origin in the rotation-induced antiresonance of the effective compressibility with its frequency at the angular velocity of the spinning cylinders, as well as in the rotational Doppler effect which breaks the chiral symmetry of the effective mass densities. Both bulk and interface-state bands exhibit remarkable variations as the filling fraction of the spinning cylinders is increased. In particular, a zero-frequency gap appears when exceeds a critical value. The uni-directional interface states bear interesting unconventional characteristics and their robust one-way transport properties are demonstrated numerically.

physics.app-ph↗

arXiv2019

Nonlocal effects in singular plasmonic metasurfaces

A local model of the dielectric response of a metal predicts that singular surfaces, such as sharp-edged structures, have a continuous absorption spectrum and extreme concentration of energy at the singularity. Here we show that nonlocality drastically alters this picture: the spectrum is now discrete and energy concentration, though still substantial, is greatly reduced.

cond-mat.mes-hall↗

arXiv2018

Multiple Weyl and Double-Weyl Points in an Elastic Chiral Lattice

We show that Multiple Weyl and double Weyl points arise in a chiral elastic system through stacking many two-dimensional honeycomb mechanical structures. On the distinct kz plane, the band structures calculated from tight-binding model exhibit the presence of Weyl points at Brillouin vertices and double Weyl Points at Brillouin centre. Based on the tight-binding model, we design a practical chiral mechanical structure which can be fabricated by current 3D printing technology. The numerical calculation illustrates several Weyl and double-Weyl points as expected in our analysis of tight-binding model. To verify the topological feature, topological charges of every degeneracy are calculated. Within these Weyl points, we theoretically prove that the existence of topologically protected surface modes, and their robustness against defects are also demonstrated.

cond-mat.mes-hall↗

arXiv2016

Elastic Spin Hall effect in Mechanical Graphene

We show that spin-orbit interaction and elastic spin-Hall effect can exist in a classical mechanical system consisting of a two-dimensional honeycomb lattice of masses and springs. The band structure shows the presence of splitting at K point induced by the difference of longitudinal and transverse elastic constant, and this splitting can be regarded as an effective Dresselhaus-type spin-orbit coupling. Interestingly, as an initial displacement away from the equilibrium is applied, the time evolution simulation shows that waves of different spin polarization propagates along different directions at the Gamma and K point, which is characteristic of spin-Hall effect. Several cases for spin-Hall effect are also discussed.

cond-mat.mes-hall↗

arXiv2014

Coriolis Force Induced Quantum Hall Effect for Phonons

A two-dimensional mass-spring system with Honeycomb lattice for mimicking phononic quantum Hall effect is proposed. Its band structure shows the existence of Dirac cones and unconventional edge states that is similar to the vibrational modes in graphene. Interestingly, as the system is placed on a constantly rotational coordinate system, the Coriolis force resulted from the non-inertial reference frame provides a possibility to break the time-reversal symmetry. Thus, caused from topologically non-trivial band gaps, phononic edge states are present between bands, which are verified by the calculation of Chern numbers for corresponding bands.

cond-mat.mes-hall↗