Quantum Physics
Monogamy of quantum steering in exciton–cavity optomechanical system
Hamza Harraf, Mohamed Amazioug and Rachid Ahl Laamara
In this work, we study a theoretical scheme to investigate the monogamy of
quantum steering in a hybrid
exciton–cavity optomechanical (EOM) system. Within the Gaussian-state formalism, we quantify the steerability among the
exciton,
photon, and mechanical modes in both the steady-state and dynamical regimes. We establish and verify CKW-type monogamy inequalities for Gaussian steering and demonstrate that the distribution of bipartite steering among the three modes can be controlled through the system parameters. We further examine the influence of thermal noise and temporal
evolution on the steering properties and the corresponding monogamy relations. Our results show that increasing the temperature generally suppresses the strength of Gaussian steering and modifies the degree of steering sharing imposed by the CKW-type monogamy relations. In contrast, in the dynamical regime, the steerability can increase with
evolution time over suitable temporal windows, indicating that the transient dynamics can be exploited to enhance
quantum correlations. These results highlight the potential of hybrid
exciton–optomechanical platforms for controllable
quantum correlations and provide a promising route toward the generation and manipulation of multipartite
quantum resources.
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Strongly Correlated Electrons
Dispersion of low-energy optical excitations in NiPS$_3$ explained by singlet polaron theory
I. J. Hamad, C. S. Helman, A. E. Feiguin et al. (+2 more)
Optical and resonant inelastic X-ray scattering (RIXS) experiments in the van der Waals antiferromagnet NiPS$_3$ have revealed narrow excitonic resonances near 1.5 eV whose microscopic origin remains under debate. In this work we study the momentum dependence of these excitations using the singlet-polaron theory (SPT) previously developed for NiPS$_3$. Within its framework, we calculate the spectral function of the corresponding effective model and extract the dispersion of the resulting quasiparticles. The theory naturally predicts two singlet excitations whose dynamics arise from their propagation in the zig-zag antiferromagnetic background ($S=1$) coupled to two-
magnon processes. We show that the dispersion of the lowest-energy quasiparticle agrees very well with the excitonic dispersion measured by RIXS, reproducing both its overall shape and bandwidth along high-
symmetry directions of the Brillouin zone. Our results provide a consistent interpretation of the optical excitations in terms of dispersive singlet polarons, and suggest that similar mechanisms may govern excitonic dynamics in other layered van der Waals antiferromagnets.
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All authors I. J. Hamad, C. S. Helman, A. E. Feiguin, L. O. Manuel, A. A. Aligia
Biological Physics · Cross-listed from q-bio.QM
Data-Driven Discovery of a Hyperelastic Strain-Energy Function for Veins Using Constitutive Artificial Neural Networks
Marisa Bazzi, Divya Adil, Gavin Mays et al. (+4 more)
Veins are commonly subjected to altered mechanical loading in clinical settings such as vein grafting, arteriovenous fistula creation, and tissue-engineered vascular graft implantation, making accurate constitutive models of venous tissue clinically important. Venous mechanical behavior differs characteristically from that of arteries, and existing constitutive models struggle to simultaneously fit the circumferential and axial stress-stretch responses across vein types. Here, we present a constitutive artificial neural network (CANN) framework that discovers a compact, interpretable hyperelastic constitutive model from biaxial mechanical data across three types of veins (saphenous, jugular, and inferior vena cava). The framework incorporates an expanded candidate function library with structurally motivated terms representing progressive fiber recruitment and fiber-family interactions. Sobol sensitivity analysis, correlation-based
pruning, and response-level family collapse were then used to reduce the discovered basis to a compact strain-energy density function (SEF). The resulting eight-term SEF achieved significantly higher fitting accuracy than established venous constitutive models across all three types of veins $(R^2>0.9, p<0.01)$. These findings establish a framework for constitutive model discovery in veins and propose a candidate constitutive form for further validation across larger, independent cohorts.
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All authors Marisa Bazzi, Divya Adil, Gavin Mays, Ellen Kuhl, Christopher K. Breuer, Jay D. Humphrey, Alison L. Marsden
Mathematical Physics
Non-Intrusive Balancing for Data-Driven Model Reduction with Oblique Projections
Alberto Padovan
Non-intrusive reduced-order modeling is essential for systems simulated with black- or gray-box solvers, yet computing accurate data-driven models remains challenging when the dynamics exhibit large-amplitude transient energy growth. This is because state-of-the-art non-intrusive methods typically rely on orthogonal projection onto high-energy linear or nonlinear
manifolds identified by minimizing static reconstruction losses, which truncates low-energy, yet dynamically important, states. Intrusive methods such as Balanced Truncation and its extensions address this issue by using adjoint information to define dynamics-aware oblique projections. Here, we show that balancing-based oblique projections for nonlinear systems can instead be computed non-intrusively from forward simulation data. Specifically, we develop a framework to compute the nonlinear empirical reachability Gramian and balance it against its observability counterpart, projected onto a suitable restriction subspace. This procedure provably recovers the oblique projection of Balanced Truncation when the dynamics are linear and the range of either Gramian is contained in the restriction subspace. Moreover, in the linear case and in the absence of adjoint information, we show that the minimax-optimal restriction subspace spans the dominant eigenspaces of the reachability Gramian, which informs an efficient balancing
algorithm with cost comparable to a standard SVD. Once the oblique projection is computed, we use Operator Inference to learn the latent-space dynamics on its range. The method is demonstrated on several examples of increasing complexity, including the three-dimensional incompressible flow past a wing with $8\times 10^7$ degrees of freedom. In all examples, the Balanced Operator Inference models significantly outperform their POD-based counterparts, reducing forecasting error by up to two orders of magnitude.
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Materials Science
Transition-Metal Chalcogenide Nanowires: A First-Principles Study of Stability, Electronic Structure, and Mechanical Response
Danilo de Araújo Moura, Flavio Bento de Oliveira and Andreia Luisa da Rosa
Subnanometer transition-metal chalcogenide nanowires provide a one-dimensional platform in which electronic functionality and mechanical response can be tuned through chemical composition. Here, density functional theory calculations are combined with machine-learning force-field (MLFF) molecular dynamics to investigate MoS, MoSe, MoTe, WS, WSe, and WTe nanowires. The optimized structures are dynamically stable within the harmonic approximation, and their electronic character evolves systematically across the chalcogen series: MoS, MoSe, WS, and WSe are metallic, whereas MoTe and WTe are semiconducting, with HSE06 band gaps of 0.52 and 0.20 eV, respectively. The effective axial stiffness decreases from sulfides to selenides and tellurides, consistent with the increase in metal–chalcogen bond length; using a circular effective cross section, the corresponding Young moduli range from 392 to 718 GPa. All six nanowires have negative formation energies relative to the selected elemental reference phases. MLFF trajectories extending to 2.5 ns at 300 K preserve the one-dimensional morphology and local atomic order, providing evidence of finite-temperature dynamical stability on the simulated time scale. The corresponding MLFF molecular-dynamics energy traces are shown in. We further examine the response of the nanowires to axial strain and
curvature, including strain-induced band-gap modulation in the tellurides. These results establish composition and mechanical deformation as complementary routes for tuning the electronic and mechanical properties of ultrathin transition-metal chalcogenide nanowires and support their further investigation as components of flexible nanoelectronic systems.
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Space Physics
Validation of Space Weather Forecasting at Leonid Space
Scott Shambaugh
We validate Leonid Space's space weather forecasts through comprehensive cross-validation of retroforecasts scored against the entire F10.7 and Ap historical record. We built a unified forecast model that jointly forecasts F10.7 and Ap on all timescales from 3 hours up to multi-decade chains of future solar cycles. This was used to generate an archive of historical 15-year retroforecasts, after performing a leave-one-out fit of the model on held-out data and conditioning only on historical data available at the time. The accuracy of this archive was scored against measured space weather indices at all lookahead horizons from 1 day to 15 years, using the continuous ranked probability score (CRPS) as the primary quality metric. All other publicly available F10.7 and Ap forecast archives were scored using the same approach, including NASA's MSAFE and Schatten forecasts, SWPC's 27-day, 45-day, and Solar Cycle predictions, SWPC/USAF's RSGA, SIDC's Ursigram, CLS, Athens, KSO, BGS, SEPC's 3-day and 27-day forecasts, AFRL/NSO's SIFT, and BoM. Taken together, these 15 flux forecasts and 12 Ap forecasts compared on common lookahead metrics make up the most comprehensive cross-comparison of space weather forecasts we are aware of. Over a common forecast interval since 2000, Leonid had the lowest CRPS prediction error of any F10.7 or Ap prediction model: strictly lowest for Ap at all lookaheads and for F10.7 up to 5 years, and parity with MSAFE after 5 years. Much of this performance comes from our well-calibrated uncertainty bands, and we urge space weather forecasters to include calibrated uncertainties with their predictions and to issue retroforecast archives that can be used to rigorously evaluate their generating models.
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Quantum Physics
Signal-to-noise problems in fault-tolerant quantum computation
Hyunwoo Oh
Quantum computation offers a promising alternative to classical Monte Carlo methods by naturally avoiding sign problems through
unitary evolution. A common misconception follows from this: because
quantum simulation sidesteps the sign problem, it is often assumed to be an essentially perfect substitute for classical sampling. This is false—
quantum measurements are intrinsically
stochastic, and estimating observables often requires a number of samples that grows exponentially with system size, time separation, or inverse temperature, exactly as in the classical signal-to-noise problem. In this work, we analyze the origin and structure of signal-to-noise problems in
quantum computation, drawing parallels with classical Monte Carlo, and demonstrate that such noise persists even in sign-problem-free regimes. We discuss strategies to mitigate it, in particular a
quantum generalization of Stein control variates construction, in which unbiased
estimators are built from operator commutators $[X,A]$ and their discrete diagonal counterparts, and validate the approach with exactly solvable numerical examples that quantify the achievable variance reduction. Our results underscore that variance reduction, not merely sign-problem avoidance, is required to make
quantum algorithms practically viable for many-body physics.
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High Energy Physics (Phenomenology)
Cosmology & Astrophysics of the Dark Dimension with Bulk Majorana Neutrinos
Luis A. Anchordoqui and Cumrun Vafa
Recently, the possibility of having sterile Majorana
neutrinos charged under $B-L$ gauge
symmetry in the bulk of the dark dimension has been explored. We point out a cosmological restriction on the Majorana mass of bulk
neutrinos leading to mass $\gtrsim 100~{\rm GeV}$. This avoids the over-production of Kaluza-Klein
neutrino towers in the early universe thus resolving the cosmological
neutrino catastrophe of extra dimension scenarios. If the mass of the bulk
neutrino is at the lower end of this bound, it can potentially also explain the recently observed Fermi
halo excess on gamma rays through the evaporation of long-lived 5d (i.e. dark) black holes through Hawking radiation to bulk
neutrinos, which promptly decay into standard model particles.
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Pattern Formation and Solitons
Selection of Marginally Stable Patterns by Boundary Conditions
Jacob Daniels, Simon Eskin, Tel Fahrendholz et al. (+1 more)
We study the effect of boundary conditions on the selection of wavenumbers in pattern-forming systems. Prior work established that, for a large class of boundary conditions,
equilibria only within a narrow band of wavenumbers are compatible with the boundary. We demonstrate here that for a large class of initial conditions, solutions evolve towards an extremal member of this narrow band of
equilibria. In fact, this extremal member is neutrally stable, nonlinearly unstable, and the convergence is realized through a series of snapping events at the boundary. We observe this behavior in simulations of the Swift-Hohenberg equation when the pattern forming region is confined to a large spatial interval through a parameter quench. We prove the convergence in a phase-
diffusion approximation using comparison principles and astutely chosen subsolutions that mimic the snapping behavior.
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All authors Jacob Daniels, Simon Eskin, Tel Fahrendholz, Arnd Scheel
Superconductivity
Local Suppression of Superconductivity in Niobium Films by Focused Silicon Ion Implantation
Rochelle Y. Qu, Shunsuke Nishimura, Max Proepper et al. (+8 more)
Magnetic flux trapped in a superconducting
circuit shifts the critical currents of nearby Josephson junctions and disturbs the operation of the
circuit. The usual remedy is a moat etched through the ground plane to hold the flux away from the logic. We report direct write silicon ion implantation with a focused ion beam as a way to make moats without etching the film, by locally suppressing superconductivity in niobium (Nb). Single implanted lines were written across Nb electrodes in films of three thicknesses over two orders of magnitude in ion fluence, and the transition temperature, resistance, and critical current density of each line were measured. The transition temperature of the line falls with fluence while the surrounding Nb is unchanged, and the critical current density falls by about two orders of magnitude before the line becomes resistive at 4.2 K. The product of the critical current and the resistance of the lines follows a single power law in reduced temperature. This gives an estimate of the critical current of a line at any temperature from its transition temperature and resistance. A time dependent Ginzburg-Landau simulation indicates that an implanted region can capture and hold a
vortex. From these results we suggest a starting ion energy and fluence for implanted moats in a 100 nm Nb ground plane at 4.2 K and estimate the equivalent broad beam fluence.
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All authors Rochelle Y. Qu, Shunsuke Nishimura, Max Proepper, Joseph J. Barrera, Alexander Brooks, Joshua Vande Berg, Achim Nadzeyka, Aravind R. Sreeja, Jay C. LeFebvre, Roger K. Lake, Shane A. Cybart
Quantum Physics
The Rényi area law conjecture is false below $\alpha=1$ in high dimensions
Tomotaka Kuwahara
Area laws express the expectation that
entanglement in gapped
quantum ground states scales with a boundary rather than a volume. In one dimension this holds for every Rényi
entropy, and the Rényi area-law
conjecture asserts the same in higher dimensions for each fixed $0<\alpha<1$. Here we disprove this
conjecture in every spatial dimension two and higher. We construct finite-range
Hamiltonians with fixed local dimension, bounded interaction strength, unique ground states and a uniform spectral gap, whose ground states exhibit volume-law Rényi
entanglement while obeying a von Neumann area law and remaining connected to product states through uniformly gapped local paths. The mechanism is error-space complexity: locally identifiable components of arbitrarily small weight can encode states with high
entanglement complexity. We also establish the worst-case rank-error trade-off for approximate ground-state projectors, a key tool in one-dimensional area-law proofs. At fixed gap, the optimal Schmidt rank at projection error $\epsilon$ across a planar cut of cross-section $A$ scales as $\exp[\tilde{\Theta}((A\log\epsilon^{-1})^{2/3})]$ when $\log\epsilon^{-1}\gtrsim A$. Thus $\alpha=1$ is the sharp threshold for a universal Rényi area law within this adiabatically connected class.
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Strongly Correlated Electrons
Superlattice-Stabilized Fractional Chern Insulators in a "Berry Basin" Model
Yongxin Zeng and Andrew J. Millis
The discovery of integer and fractional Chern
insulators in rhombohedral
graphene, following their discovery in the isolated topological flat band in twisted MoTe$_2$, motivates a search for the conditions under which an electronic band can host a topological correlated state. In this Letter we introduce a “Berry basin" model which captures the essential features of rhombohedral
graphene: a dispersive band with a flat bottom, momentum-space winding of a “layer" degree of freedom, and Coulomb interactions, while also including periodic potentials, enabling controlled studies of the interplay of
quantum geometry, superlattice modulation, and electron-electron interactions in producing correlated topological states beyond the isolated topological band paradigm. While integer Chern
insulators emerge at strong coupling without a superlattice potential, stabilizing the fractional state requires nonzero potential for all interaction strengths we access. We provide insight into the greater robustness of integer and fractional Chern
insulators in rhombohedral
graphene when electrons are polarized away from the moiré interface. Our results establish a new class of systems that host robust fractional Chern
insulators and provide a controlled numerical platform to test competing theories of interacting topological phases.
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Materials Science
Nucleation at the GST–oxide interface and beam-driven ordering in amorphous Ge–Sb–Te: HAADF, EDS and electron pair distribution functions across a 4D-STEM dose series
Mridul Kumar, Kirill Sobolev, Alexander Upcher et al. (+1 more)
Where
crystal nuclei form in amorphous phase-change materials decides how they switch. We study six successive 4D-STEM scans, with simultaneous HAADF and EDS data, of a magnetron-sputtered Ge-Sb-Te (GST) film, restricted to the GST layer and its interface with the oxide beneath it. Nucleation sites do not differ in composition or number density: the
nuclei lie on the same robust HAADF-EDS relation as the
matrix, and at fixed HAADF the spread of the summed EDS signal equals its Poisson counting noise (ratio 1.03 +- 0.05). The
nuclei are nevertheless crystalline and stand out in the 4D-STEM max-intensity virtual image (median z = 11.0) but not in HAADF (z = 1.3) or EDS (z = 0.3). We classify the film in four ways (HAADF intensity, I(q) phase mapping, PCA of the whole diffraction patterns and a self-supervised SimCLR encoder) and compare the electron pair distribution functions (PDFs) of all classes after calibrating reciprocal space on the Au cap. All bulk classes share one short-range structure (first shell 2.70-2.74 Å); towards the interface the first sharp diffraction peak (FSDP) moves to lower q, and every method isolates a thin interface-edge environment with a shorter or missing first shell. The I(q) classification isolates, in every scan, an interface environment that holds 62-100% of the
nucleus pixels (1.2-2.5-fold above depth) and persists when the
nucleus pixels are removed before classification. The interface, rather than a distinct composition or density of the nucleating volume, therefore marks where
nuclei form. Over 4.7e3 e/Å^2 the HAADF signal falls by 17%, the first shell shortens by 0.03 Å and the FSDP narrows by 9%, apparently ordering the film as it damages it. All analyses used PySTEMLab, an interactive 4D-STEM analysis environment developed for this work.
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All authors Mridul Kumar, Kirill Sobolev, Alexander Upcher, Yevgeny Rakita
Applied Physics
Directivity Estimates and Tolerance Tradeoffs in the Presence of Random Perturbations
Kurt Schab, Lukas Jelinek, Miloslav Capek et al. (+1 more)
The practicality of realizing high-directivity sources is studied using a generalized sensitivity metrics. These measures are based on the error model adopted in previous studies on array tolerance, but account for heterogeneous array characteristics in an arbitrary source-expansion basis, making it applicable to the study of continuous sources, ideal uncoupled arrays, and heterogeneous arrays with mutual coupling. The formulation provides the ensemble average of realized directivity under the selected error model, making it a fast predictor of anticipated directivity reduction due to source perturbation. The data required to compute these predictions are straightforward to obtain via simulation or measurement, with a significant simplification when the system can be approximated as lossless. The directivity and the proposed tolerance measures allow for the formulation of optimization problems illustrating the tradeoff between these measures. Several examples demonstrate these tradeoffs, special cases, comparison to previous estimates of maximum directivity, and the accuracy of sensitivity as a predictor of statistical performance over large ensembles of design realizations.
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All authors Kurt Schab, Lukas Jelinek, Miloslav Capek, Mats Gustafsson
Soft Condensed Matter
Reparameterizing GFN1-xTB for Ionic Liquids
F. Stavarache, S. Calero and J. M. Vicent-Luna
Ionic
liquids are materials whose properties can be tailored for a wide range of applications, but their chemical diversity and complex electronic structure make systematic screening using
quantum-mechanical methods computationally demanding. Semiempirical
quantum methods offer an alternative, although their accuracy depends on their parameterization. We investigate the reparameterization of the DFTB method GFN1-xTB for predicting structural, energetic, and electronic properties of ionic
liquids. For this purpose, we built a database containing over 14,000 conformations to construct training
datasets and explored different parameterization strategies fitted to binding energies, forces, HOMO-LUMO gaps, and geometries. Analysis of the original GFN1-xTB model reveals systematic errors in these properties, with distinct behavior for saturated and aromatic cations. Thus, we investigate two models: CXMIM-xTB, a targeted model trained on imidazolium-based ionic
liquids, and IL-xTB, a more general model designed to describe systems containing saturated and aromatic cations. CXMIM-xTB improves the description of binding energies, geometries, and frontier orbital energies while retaining computational efficiency. The model is subsequently applied to estimate electrochemical windows of ionic
liquids, providing values consistent with DFT and experimental values. IL-xTB follows a hierarchical parameterization strategy including different cation and anion families and substantially reduces the systematic errors of GFN1-xTB across the chemical space considered, providing a route for developing xTB parameterizations with broader applicability to ionic
liquids. Overall, both parameterization strategies outperform the original GFN1-xTB model, demonstrating that reparameterized methods provide an efficient approach for connecting configurational sampling with
quantum-mechanical properties of ionic
liquids.
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Materials Science
Interfacial Coupling Reshapes Nonlinear Polarization in a Spin-Defect van der Waals Heterostructure
Lena Dalifoski, Eveline Mayner and Poonam Singh
Van der Waals
heterostructures offer a direct route to couple an optically active layer to a two-dimensional
spin sensor, yet their coherent nonlinear response at interfaces remains poorly resolved. Here, we use polarization-resolved second harmonic-generation imaging to resolve four distinct regions of a hexagonal boron nitride (hBN) -based
heterostructure, native hBN,
neutron-irradiated hBN containing negatively charged boron vacancies (VB-), PbI2 and their complete overlap. The detected intensity scales quadratically with incident power, consistent with a dominant second-order optical process. Polarization scans show that adding PbI2 transforms the distorted VB- SHG anisotropy into a predominantly fourfold response with a sixfold stronger SHG than native hBN alone. This non-additive nonlinear response occurs in the same layer architecture also shown to enhance defect photoluminescence, linking
spin-defect sensitization to an interface-modified effective second-order susceptibility.
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Fluid Dynamics
Physics Foundation Models for Efficient Control of Fluid Flows
Mahindra Rautela, Shaifalee Saxena and Alexander Scheinker
We investigate whether a physics foundation model (PFM) pretrained for PDE forecasting can be repurposed for closed-loop fluid-flow control. We construct a PFM-based controller by attaching lightweight Gaussian actor and critic heads to frozen pretrained representations and train the policy using proximal policy optimization (PPO). We evaluate the approach on HydroGym's two-dimensional Kolmogorov-flow environment using vorticity observations at \(64\times64\) and \(128\times128\) resolutions and Reynolds numbers \(\mathrm{Re}=100\) and \(200\). Across these settings, we compare the frozen PFM controller against a baseline MLP policy trained with the same PPO framework. The PFM controller achieves consistently higher reward while requiring smaller executed action magnitudes over training, indicating improved control performance with reduced control effort. These results provide initial evidence that representations learned through self-supervised next-frame prediction can be transferred directly to closed-loop fluid flow control. Project page: https://mahindrautela.github.io/morph.
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Strongly Correlated Electrons
Spectral Mapping Theorem between SU(N) and SU(Ns/N) Heisenberg Models and Exact Diagonalization of SU(4) and SU(7) Long-Range Ordered Phases on the Triangular Lattice
Samuel Gozel and Pierre Nataf
We first show that, for the SU(N) Heisenberg model with isotropic two-site interactions on an arbitrary
lattice of Ns sites, the full spectrum in its singlet sector (when N divides Ns) is the negative of the full spectrum in its singlet sector of the SU(Ns/N) Heisenberg model defined on the same
lattice. This
theorem, valid for models with the fundamental irreducible representation (irrep) at each
lattice site, follows naturally from a transposition operation in the basis of Standard Young Tableaux (SYTs). Second, this basis – previously recognized as particularly convenient for exact diagonalization (ED) of SU(N) Heisenberg models – admits an efficient,
memory-saving implementation, thereby enabling large-scale diagonalizations for unprecedented system sizes Ns and numbers of colors N>3. We apply these ideas to an ED study of the SU(4) and SU(7) Heisenberg models on the triangular
lattice (TL), extending the calculations up to Ns=28 sites. In particular, starting from the SU(4) case, whose nearest-neighbor ground state remains debated, we confirm that next-nearest-neighbor couplings stabilize four-sublattice long-range order. We further find that increasing the number of colors from N=4 to N=7 provides another route toward a Néel-like ground state, even without such additional couplings. N = 4 to N = 7 provides another route toward a Néel-like ground state, even without such additional couplings.
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Applied Physics
Sub-Micron Gate $\beta-Ga_{2}O_{3}$ FinFETs with Current Density $>$ 750 mA/mm and Ion/Ioff Ratio $>$ $10^{9}$
Nabasindhu Das, Cameron Gorsak, Pushpanshu Tripathi et al. (+7 more)
In this work, we demonstrate submicron-gate $\beta-Ga_{2}O_{3}$ FinFETs that integrate Si delta-doped channels with selectively regrown n++ source/drain contacts. The devices employ 100 nm-wide fins to improve electrostatic control of a high sheet charge density channel of $3.3\times 10^{13}$ cm-2. A 150 nm-gate-length FinFET exhibits a maximum drain current density of 764 mA/mm at VGS = 1 V and VDS = 10 V, an on-resistance of 9.1 $\Omega$.mm, and an Ion/Ioff ratio exceeding $10^9$. The device also shows a peak transconductance of 43 mS/mm and de-embedded $f_{T}/f_{MAX}$ values of 6.3/2.0 GHz. Pulsed I-V measurements indicate ~20 % current collapse, attributed primarily to trapping at etched fin sidewalls and the $Al_{2} O_{3}$/ $\beta-Ga_{2}O_{3}$ interface. These results show that delta-doped $\beta-Ga_{2}O_{3}$ FinFETs can simultaneously achieve high drive current, strong current modulation, and GHz-frequency operation, providing a scalable device platform for future power and RF electronics.
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All authors Nabasindhu Das, Cameron Gorsak, Pushpanshu Tripathi, Ankita Kashyap, Noor Jahan Nipu, Advait Gilankar, Hari Nair, Uttam Singisetti, Trevor Thornton, Nidhin Kurian Kalarickal
Mathematical Physics · Cross-listed from math.AP
Plane wave representations for wave scattering on a sphere
Valentin D. Kunz, Andrey V. Shanin and Raphael C. Assier
Motivated by three-dimensional wave diffraction by conical shapes, we consider the two-dimensional problem of wave scattering on the real sphere $\mathcal{S}^2$ resulting from a point-source incidence on a scatterer $\mathbb{S}$. Using the recently introduced notion of plane waves on $\mathcal{S}^2$ as well as recent results on the Laplace–Beltrami Green's function $G$ on $\mathcal{S}^2$, we derive three plane-wave representations for the scattered field $u$. We then explain how $u$ can be analytically continued to the complexified sphere $\mathcal{S}^2_{\mathbb{c}}$. This allows us to formulate a complexified version of Green's third identity, and to provide a characterisation of complex sources. All our results are then used to draw strong analogies between planar and spherical scattering problems, notably through the introduction of directivities.
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