arXiv subjects

R. Huang

Publications and source records attributed to R. Huang.

At least 19 recordsLinked to original sources

arXiv2026

Extending Field Limits in Nanoscale Magnetic Imaging with Metamaterial-inspired Magnetic Flux Concentrators

Many nanoscale magnetic imaging techniques are constrained by the maximum magnetic field that can be applied during measurements, due to geometrical limitations or interactions with the probe or the detected signal (e.g., electrons). Here, it is demonstrated that sample-integrated metamaterial-inspired magnetic flux concentrators (MFCs) locally amplify magnetic fields, allowing observation of magnetization processes beyond instrumental limits. Micrometer-sized MFCs fabricated directly on the samples are tested in photoemission electron microscopy experiments employing X-ray magnetic circular dichroism as magnetic contrast mechanism. At low applied fields, substantial amplification factors enable observation of magnetization reversal in a chain of magnetite nanoparticles synthesized by magnetotactic bacteria at an applied field of 8 mT, substantially smaller than the 50 mT predicted by simulations in absence of MFCs. At higher fields, the field enhancement extends the accessible field range by a factor of five, enabling for the first time, imaging of the field-dependent magnetic domain structure evolution of an isolated giant magnetofossil. Finally, we show how MFC geometry and material parameters can be tuned to optimize performance considering sample and experimental constraints, providing a tunable and broadly applicable strategy for extending the accessible field range in a wide variety of nanoscale magnetic imaging techniques.

cond-mat.mtrl-sci↗

arXiv2026

Type-Aware Retrieval-Augmented Generation with Dependency Closure for Solver-Executable Industrial Optimization Modeling

Automated industrial optimization modeling requires reliable translation of natural-language requirements into solver-executable code. However, large language models often generate non-compilable models due to missing declarations, type inconsistencies, and incomplete dependency contexts. We propose a type-aware retrieval-augmented generation (RAG) method that enforces modeling entity types and minimal dependency closure to ensure executability. Unlike existing RAG approaches that index unstructured text, our method constructs a domain-specific typed knowledge base by parsing heterogeneous sources, such as academic papers and solver code, into typed units and encoding their mathematical dependencies in a knowledge graph. Given a natural-language instruction, it performs hybrid retrieval and computes a minimal dependency-closed context, the smallest set of typed symbols required for solver-executable code, via dependency propagation over the graph. We validate the method on two constraint-intensive industrial cases: demand response optimization in battery production and flexible job shop scheduling. In the first case, our method generates an executable model incorporating demand-response incentives and load-reduction constraints, achieving peak shaving while preserving profitability; conventional RAG baselines fail. In the second case, it consistently produces compilable models that reach known optimal solutions, demonstrating robust cross-domain generalization; baselines fail entirely. Ablation studies confirm that enforcing type-aware dependency closure is essential for avoiding structural hallucinations and ensuring executability, addressing a critical barrier to deploying large language models in complex engineering optimization tasks.

cs.SE↗

arXiv2026

Probing atom-surface interactions from tunneling-time measurements via rotation-transport on an atom chip

We propose a novel method to measure the interaction between an ultracold gas of neutral atoms and a surface. This solution combines an optical dipole trap reflected by the surface, a magnetic trap formed by current carrying wires embedded below the surface, and a rotation of the surface itself. It allows to adiabatically transport a $^{87}$Rb BEC from few $\mu$m to few hundred nm of the surface. At such distances, atom-surface interaction strongly affects the trapping potential, causing an increase of the tunneling rate towards the surface. In this paper, we show that the measurement of the lifetime of the cloud and its comparison to a tunneling model will allow to extract the Casimir-Polder (CP) force coefficient in the retarded regime ($c_4$). Our model includes noise-induced heating, calibration biases of experimentally controlled parameters and accuracy of the atom lifetime measurement. Using typical trapping parameters and experimental uncertainties, we numerically estimate the relative uncertainty of $c_4$ to be 10%. This method can be implemented with any atomic species that can be magnetically and optically trapped.

cond-mat.quant-gas↗

arXiv2025

Signatures of a high-temperature collective electronic phase with superconductivity-like characteristics and a giant pressure effect in networks of boron-doped ultrathin carbon nanotubes

We present data consistent with a high-temperature collective electronic phase with superconductivity-like characteristics in three dimensional networks of boron doped, ultrathin carbon nanotubes (CNTs) grown inside the 5 Angstrom channels of ZSM-5 zeolite. Confinement stabilizes (2,1) CNTs that are otherwise dynamically unstable, while boron doping shifts the Fermi level towards a van Hove singularity, as supported by ab-initio calculations. The resulting CNT network exhibits multiple, mutually consistent signatures of an electronic condensate with the typical characteristics of a high temperature superconductor at ambient pressure. DC magnetization and AC susceptibility measurements reveal the onset of a Meissner response between 220 and 250K, with compacted samples achieving up to 93 percent of full diamagnetic screening. Electrical transport shows a sharp resistive transition with extrapolated Tc = 239K and vanishing resistance in optimized samples. Specific heat measurements display a reproducible anomaly at 233 to 236 K that broadens under magnetic field, consistent with strong fluctuations. Point contact spectroscopy identifies three energy gaps, including a leading gap of 30 meV whose temperature dependence follows BCS expectations for Tc = 224K, and exhibits particle-hole symmetry and Andreev reflection. Remarkably, applying pressures below 0.1 kbar enhances Tc by nearly 100K and modulates the room temperature resistance by more than three orders of magnitude, suggesting a pressure driven 1D to 3D crossover in the CNT network. These results identify boron doped ultrathin CNT networks as a promising carbon-based platform for near ambient temperature superconductivity and reveal an unusually large pressure sensitivity with potential technological relevance.

cond-mat.supr-con↗

arXiv2024

Searching for Beyond the Standard Model physics using the improved description of $^{100}$Mo $2\nu\beta\beta$ decay spectral shape with CUPID-Mo

The current experiments searching for neutrinoless double-$\beta$ ($0\nu\beta\beta$) decay also collect large statistics of Standard Model allowed two-neutrino double-$\beta$ ($2\nu\beta\beta$) decay events. These can be used to search for Beyond Standard Model (BSM) physics via $2\nu\beta\beta$ decay spectral distortions. $^{100}$Mo has a natural advantage due to its relatively short half-life, allowing higher $2\nu\beta\beta$ decay statistics at equal exposures compared to the other isotopes. We demonstrate the potential of the dual read-out bolometric technique exploiting a $^{100}$Mo exposure of 1.47 kg $\times$ y, acquired in the CUPID-Mo experiment at the Modane underground laboratory (France). We set limits on $0\nu\beta\beta$ decays with the emission of one or more Majorons, on $2\nu\beta\beta$ decay with Lorentz violation, and $2\nu\beta\beta$ decay with a sterile neutrino emission. In this analysis, we investigate the systematic uncertainty induced by modeling the $2\nu\beta\beta$ decay spectral shape parameterized through an improved model, an effect never considered before. This work motivates searches for BSM processes in the upcoming CUPID experiment, which will collect the largest amount of $2\nu\beta\beta$ decay events among the next-generation experiments.

nucl-ex↗

arXiv2023

Measurement of the $2\nu\beta\beta$ decay rate and spectral shape of $^{100}$Mo from the CUPID-Mo experiment

Neutrinoless double beta decay ($0\nu\beta\beta$) is a yet unobserved nuclear process which would demonstrate Lepton Number violation, a clear evidence of beyond Standard Model physics. The process two neutrino double beta decay ($2\nu\beta\beta)$ is allowed by the Standard Model and has been measured in numerous experiments. In this letter, we report a measurement of $2\nu\beta\beta$ decay half-life of $^{100}$Mo to the ground state of $^{100}$Ru of $(7.07~\pm~0.02~\text{(stat.)}~\pm~0.11~\text{(syst.)})~\times~10^{18}$~yr by the CUPID-Mo experiment. With a relative precision of $\pm~1.6$ \% this is the most precise measurement to date of a $2\nu\beta\beta$ decay rate in $^{100}$Mo. In addition, we constrain higher-order corrections to the spectral shape which provides complementary nuclear structure information. We report a novel measurement of the shape factor $\xi_{3,1}=0.45~\pm 0.03~\text{(stat.)} \ \pm 0.05 \ \text{(syst.)}$, which is compared to theoretical predictions for different nuclear models. We also extract the first value for the effective axial vector coupling constant obtained from a spectral shape study of $2\nu\beta\beta$ decay.

nucl-ex↗

arXiv2023

The background model of the CUPID-Mo $0\nu\beta\beta$ experiment

CUPID-Mo, located in the Laboratoire Souterrain de Modane (France), was a demonstrator for the next generation $0\nu\beta\beta$ decay experiment, CUPID. It consisted of an array of 20 enriched Li$_{2}$$ ^{100}$MoO$_4$ bolometers and 20 Ge light detectors and has demonstrated that the technology of scintillating bolometers with particle identification capabilities is mature. Furthermore, CUPID-Mo can inform and validate the background prediction for CUPID. In this paper, we present a detailed model of the CUPID-Mo backgrounds. This model is able to describe well the features of the experimental data and enables studies of the $2\nu\beta\beta$ decay and other processes with high precision. We also measure the radio-purity of the Li$_{2}$$^{100}$MoO$_4$ crystals which are found to be sufficient for the CUPID goals. Finally, we also obtain a background index in the region of interest of 3.7$^{+0.9}_{-0.8}$(stat)$^{+1.5}_{-0.7}$(syst)$\times10^{-3}$counts/$\Delta$E$_{FWHM}$/mol$_{iso}$/yr, the lowest in a bolometric $0\nu\beta\beta$ decay experiment.

hep-ex↗

arXiv2022

New measurement of double beta decays of $^{100}$Mo to excited states of $^{100}$Ru with the CUPID-Mo experiment

The CUPID-Mo experiment, located at Laboratoire Souterrain de Modane (France), was a demonstrator experiment for CUPID. It consisted of an array of 20 Li$_2^{100}$MoO$_4$ (LMO) calorimeters each equipped with a Ge light detector (LD) for particle identification. In this work, we present the result of a search for two-neutrino and neutrinoless double beta decays of $^{100}$Mo to the first 0$^+$ and $2^+$ excited states of $^{100}$Ru using the full CUPID-Mo exposure (2.71 kg$\times$yr of LMO). We measure the half-life of $2\nu\beta\beta$ decay to the $0^{+}_1$ state as $T_{1/2}^{2\nu \rightarrow 0_1^+}=7.5\pm 0.8 \ \text{(stat.)} \ ^{+ 0.4}_{-0.3} \ \text{(syst.)} )\times 10^{20} \ \mathrm{yr}$. The bolometric technique enables measurement of the electron energies as well as the gamma rays from nuclear de-excitation and this allows us to set new limits on the two-neutrino decay to the $2_1^+$ state of $T^{2\nu \rightarrow 2_1^+}_{1/2}>4.4\times 10^{21} \ \mathrm{yr} \ \text{(90 % c.i.)}$ and on the neutrinoless modes of $T_{1/2}^{0\nu\rightarrow 2_1^+}>2.1\times10^{23} \ \mathrm{yr}\ \text{(90 % c.i.)}$, $T_{1/2}^{0\nu\rightarrow 0_1^+}>1.2\times10^{23} \ \mathrm{yr}\ \text{(90 % c.i.)}$. Information on the electrons spectral shape is obtained which allows us to make the first comparison of the single state (SSD) and higher state (HSD) $2\nu\beta\beta$ decay models for the $0_1^+$ excited state of $^{100}$Ru.

nucl-ex↗

arXiv2021

New Limit for Neutrinoless Double-Beta Decay of $^{100}$Mo from the CUPID-Mo Experiment

The CUPID-Mo experiment at the Laboratoire Souterrain de Modane (France) is a demonstrator for CUPID, the next-generation ton-scale cryogenic $0νββ$ experiment. It consists of a 4.2 kg array of 20 enriched Li$_{2}$$^{100}$MoO$_4$ scintillating bolometers to search for the lepton number violating process of $0νββ$ decay in $^{100}$Mo. With more than one year of operation (2.16 kg$\times$yr of physics data), no event in the region of interest and hence no evidence for $0νββ$ is observed. We report a new limit on the half-life of $0νββ$ decay in $^{100}$Mo of $T_{1/2} > 1.5 \times 10^{24}\,$yr at 90 % C.I. The limit corresponds to an effective Majorana neutrino mass $\langle m_{ββ} \rangle$ $<$ (0.31--0.54)$\,$eV, dependent on the nuclear matrix element in the light Majorana neutrino exchange interpretation.

nucl-ex↗

arXiv2021

Pulse Shape Discrimination in CUPID-Mo using Principal Component Analysis

CUPID-Mo is a cryogenic detector array designed to search for neutrinoless double-beta decay ($0νββ$) of $^{100}$Mo. It uses 20 scintillating $^{100}$Mo-enriched Li$_2$MoO$_4$ bolometers instrumented with Ge light detectors to perform active suppression of $α$ backgrounds, drastically reducing the expected background in the $0νββ$ signal region. As a result, pileup events and small detector instabilities that mimic normal signals become non-negligible potential backgrounds. These types of events can in principle be eliminated based on their signal shapes, which are different from those of regular bolometric pulses. We show that a purely data-driven principal component analysis based approach is able to filter out these anomalous events, without the aid of detector response simulations.

physics.data-an↗

arXiv2020

Exceptional Photon Blockade: Engineering Photon Blockade with Chiral Exceptional Points

Non-Hermitian spectral degeneracies, known as exceptional points (EPs), feature simultaneous coalescence of both eigenvalues and the associated eigenstates of a system. A host of intriguing EP effects and their applications have been revealed in the classical realm, such as loss-induced lasing, single-mode laser, and EP-enhanced sensing. Here we show that a purely quantum effect, known as single-photon blockade, emerges in a Kerr microring resonator due to EP-induced asymmetric coupling between the optical modes and the nonlinearity-induced anharmonic energy-level spacing. A striking feature of this photon blockade is that it emerges at two-photon resonance which in Hermitian systems will only lead to photon-induced tunneling but not to photon blockade. By tuning the system towards to or away from an EP, one can control quantum correlations, implying the potential use of our system for frequency tunable single-photon generation and an antibunching-to-bunching light switch. Our work sheds new light on EP-engineered purely quantum effects, providing unique opportunities for making and utilizing various single-photon quantum EP devices.

quant-ph↗

arXiv2019

Precise measurement of $2νββ$ decay of $^{100}$Mo with the CUPID-Mo detection technology

We report the measurement of the two-neutrino double-beta ($2νββ$) decay of $^{100}$Mo to the ground state of $^{100}$Ru using lithium molybdate (\crystal) scintillating bolometers. The detectors were developed for the CUPID-Mo program and operated at the EDELWEISS-III low background facility in the Modane underground laboratory. From a total exposure of $42.235$ kg$\times$d, the half-life of $^{100}$Mo is determined to be $T_{1/2}^{2ν}=[7.12^{+0.18}_{-0.14}\,\mathrm{(stat.)}\pm0.10\,\mathrm{(syst.)}]\times10^{18}$ years. This is the most accurate determination of the $2νββ$ half-life of $^{100}$Mo to date. We also confirm, with the statistical significance of $>3σ$, that the single-state dominance model of the $2νββ$ decay of $^{100}$Mo is favored over the high-state dominance model.

nucl-ex↗

arXiv2019

First data from the CUPID-Mo neutrinoless double beta decay experiment

The CUPID-Mo experiment is searching for neutrinoless double beta decay in $^{100}$Mo, evaluating the technology of cryogenic scintillating Li$_{2}^{100}$MoO$_4$ detectors for CUPID (CUORE Upgrade with Particle ID). CUPID-Mo detectors feature background suppression using a dual-readout scheme with Li$_{2}$MoO$_4$ crystals complemented by Ge bolometers for light detection. The detection of both heat and scintillation light signals allows the efficient discrimination of $α$ from $γ$&$β$ events. In this proceedings, we discuss results from the first 2 months of data taking in spring 2019. In addition to an excellent bolometric performance of 6.7$\,$keV (FWHM) at 2615$\,$keV and an $α$ separation of better than 99.9\% for all detectors, we report on bulk radiopurity for Th and U. Finally, we interpret the accumulated physics data in terms of a limit of $T_{1/2}^{0ν}\,> 3\times10^{23}\,$yr for $^{100}$Mo and discuss the sensitivity of CUPID-Mo until the expected end of physics data taking in early 2020.

hep-ex↗

arXiv2019

The CUPID-Mo experiment for neutrinoless double-beta decay: performance and prospects

CUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay ($0νββ$) of $^{100}$Mo. In this article, we detail the CUPID-Mo detector concept, assembly, installation in the underground laboratory in Modane in 2018, and provide results from the first datasets. The demonstrator consists of an array of 20 scintillating bolometers comprised of $^{100}$Mo-enriched 0.2 kg Li$_2$MoO$_4$ crystals. The detectors are complemented by 20 thin cryogenic Ge bolometers acting as light detectors to distinguish $α$ from $γ$/$β$ events by the detection of both heat and scintillation light signals. We observe good detector uniformity, facilitating the operation of a large detector array as well as excellent energy resolution of 5.3 keV (6.5 keV) FWHM at 2615 keV, in calibration (physics) data. Based on the observed energy resolutions and light yields a separation of $α$ particles at much better than 99.9\% with equally high acceptance for $γ$/$β$ events is expected for events in the region of interest for $^{100}$Mo $0νββ$. We present limits on the crystals' radiopurity ($\leq$3 $μ$Bq/kg of $^{226}$Ra and $\leq$2 $μ$Bq/kg of $^{232}$Th). Based on these initial results we also discuss a sensitivity study for the science reach of the CUPID-Mo experiment, in particular, the ability to set the most stringent half-life limit on the $^{100}$Mo $0νββ$ decay after half a year of livetime. The achieved results show that CUPID-Mo is a successful demonstrator of the technology - developed in the framework of the LUMINEU project - selected for the CUPID experiment, a proposed follow-up of CUORE, the currently running first tonne-scale cryogenic $0νββ$ experiment.

physics.ins-det↗

arXiv2018

Performance of CVD Diamond Single Crystals as Side-bounce Monochromators in the Laue Geometry at High Photon Energies

We report on performance of chemical vapor deposited (CVD) single crystal diamond plates as side bounce monochromators for high photon energies ($\gtrsim$~20 keV) in the Laue geometry. Several crystals were tested in-operando high-heat-load conditions at A1 undulator station of Cornell High Energy Synchrotron Source. Up to 10$\times$ enhancement in the reflected x-ray flux was observed compared to that delivered by IIa diamond plates grown by high-pressure high-temperature method. Wavefront distortions were measured using analyzer-based x-ray diffraction imaging. Focusing of a portion of the reflected beam was demonstrated using Pt-coated mono capillary optics at a photon energy of 46 keV.

physics.ins-det↗

arXiv2017

Probing local lattice distortion in medium- and high-entropy alloys

The atomic-level tunability that results from alloying multiple transition metals with d electrons in concentrated solid solution alloys (CSAs), including high-entropy alloys (HEAs), has produced remarkable properties for advanced energy applications, in particular, damage resistance in high-radiation environments. The key to understanding CSAs radiation performance is quantitatively characterizing their complex local physical and chemical environments. In this study, the local structure of a FeCoNiCrPd HEA is quantitatively analyzed with X-ray total scattering and extended X-ray absorption fine structure methods. Compared to FeCoNiCr and FeCoNiCrMn, FeCoNiCrPd with a quasi-random alloy structure has a strong local lattice distortion, which effectively pins radiation-induced defects. Distinct from a relaxation behavior in FeCoNiCr and FeCoNiCrMn, ion irradiation further enhanced the local lattice distortion in FeCoNiCrPd due to a preference for forming Pd-Pd atomic pairs.

cond-mat.mtrl-sci↗

arXiv2017

Recursive Integral Method with Cayley Transformation

Recently, a non-classical eigenvalue solver, called RIM, was proposed to compute (all) eigenvalues in a region on the complex plane. Without solving any eigenvalue problem, it tests if a region contains eigenvalues using an approximate spectral projection. Regions that contain eigenvalues are subdivided and tested recursively until eigenvalues are isolated with a specified precision. This makes RIM an eigensolver distinct from all existing methods. Furthermore, it requires no a priori spectral information. In this paper, we propose an improved version of {\bf RIM} for non-Hermitian eigenvalue problems. Using Cayley transformation and Arnoldi's method, the computation cost is reduced significantly. Effectiveness and efficiency of the new method are demonstrated by numerical examples and compared with 'eigs' in Matlab.

math.NA↗

arXiv2009

Interplay Between Structural Randomness, Composite Disorder, and Electrical Response: Resonances and Transient Delays in Complex Impedance Networks

We study the interplay between structural and conductivity (composite) disorder and the collective electrical response in random networks models. Translating the problem of time-dependent electrical response (resonance and transient relaxation) in binary random composite networks to the framework of generalized eigenvalues, we study and analyze the scaling behavior of the density of resonances in these structures. We found that by controlling the density of shortcuts (topological randomness) and/or the composite ratio of the binary links (conductivity disorder), one can effectively shape resonance landscapes, or suppress long transient delays in the corresponding random impedance networks.

cond-mat.dis-nn↗