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Wei Qi

Publications and source records attributed to Wei Qi.

At least 55 records · Page 3Linked to original sources
arXiv2024

Experimental Secure Multiparty Computation from Quantum Oblivious Transfer with Bit Commitment

Secure multiparty computation enables collaborative computations across multiple users while preserving individual privacy, which has a wide range of applications in finance, machine learning and healthcare. Secure multiparty computation can be realized using oblivious transfer as a primitive function. In this paper, we present an experimental implementation of a quantum-secure quantum oblivious transfer (QOT) protocol using an adapted quantum key distribution system combined with a bit commitment scheme, surpassing previous approaches only secure in the noisy storage model. We demonstrate the first practical application of the QOT protocol by solving the private set intersection, a prime example of secure multiparty computation, where two parties aim to find common elements in their datasets without revealing any other information. In our experiments, two banks can identify common suspicious accounts without disclosing any other data. This not only proves the experimental functionality of QOT, but also showcases its real-world commercial applications.

quant-ph↗
arXiv2024

sTransformer: A Modular Approach for Extracting Inter-Sequential and Temporal Information for Time-Series Forecasting

In recent years, numerous Transformer-based models have been applied to long-term time-series forecasting (LTSF) tasks. However, recent studies with linear models have questioned their effectiveness, demonstrating that simple linear layers can outperform sophisticated Transformer-based models. In this work, we review and categorize existing Transformer-based models into two main types: (1) modifications to the model structure and (2) modifications to the input data. The former offers scalability but falls short in capturing inter-sequential information, while the latter preprocesses time-series data but is challenging to use as a scalable module. We propose $\textbf{sTransformer}$, which introduces the Sequence and Temporal Convolutional Network (STCN) to fully capture both sequential and temporal information. Additionally, we introduce a Sequence-guided Mask Attention mechanism to capture global feature information. Our approach ensures the capture of inter-sequential information while maintaining module scalability. We compare our model with linear models and existing forecasting models on long-term time-series forecasting, achieving new state-of-the-art results. We also conducted experiments on other time-series tasks, achieving strong performance. These demonstrate that Transformer-based structures remain effective and our model can serve as a viable baseline for time-series tasks.

cs.LG↗
arXiv2024

A new version of P-flat modules and its applications

In this paper, we introduce and study the class of $ϕ$-$w$-P-flat modules, which can be seen as generalizations of both $ϕ$-P-flat modules and $w$-P-flat modules. In particular, we obtain that the class of $ϕ$-$w$-P-flat modules is covering. We also utilize the class of $ϕ$-$w$-P-flat modules to characterize $ϕ$-von Neumann regular rings, strong $ϕ$-rings and $ϕ$-PvMRs.

math.AC↗
arXiv2024

City-LEO: Toward Transparent City Management Using LLM with End-to-End Optimization

Existing operations research (OR) models and tools play indispensable roles in smart-city operations, yet their practical implementation is limited by the complexity of modeling and deficiencies in optimization proficiency. To generate more relevant and accurate solutions to users' requirements, we propose a large language model (LLM)-based agent ("City-LEO") that enhances the efficiency and transparency of city management through conversational interactions. Specifically, to accommodate diverse users' requirements and enhance computational tractability, City-LEO leverages LLM's logical reasoning capabilities on prior knowledge to scope down large-scale optimization problems efficiently. In the human-like decision process, City-LEO also incorporates End-to-end (E2E) model to synergize the prediction and optimization. The E2E framework be conducive to coping with environmental uncertainties and involving more query-relevant features, and then facilitates transparent and interpretable decision-making process. In case study, we employ City-LEO in the operations management of e-bike sharing (EBS) system. The numerical results demonstrate that City-LEO has superior performance when benchmarks against the full-scale optimization problem. With less computational time, City-LEO generates more satisfactory and relevant solutions to the users' requirements, and achieves lower global suboptimality without significantly compromising accuracy. In a broader sense, our proposed agent offers promise to develop LLM-embedded OR tools for smart-city operations management.

math.OC↗
arXiv2024

Enhanced α particle generation via proton-boron fusion reactions in laser-modulated plasma

Aneutronic and nonradioactive properties make the proton-boron fusion a prospective candidate for fusion energy production through reactions following p+$^{11}$B$\rightarrow$3$α$ (p-$^{11}$B). However, it is difficult to achieve a thermal fusion ignition, since the low reaction cross-sections for center-of-mass energy below $\sim$100 keV. To realize fusion energy gain, it is essential to consider utilization of the maximum cross-section at the resonant peak of p-$^{11}$B fusion, and explore the nuclear reactions in plasma environment. In this work, p-$^{11}$B reactions triggered by interactions between energetic proton beams and laser-ablated boron plasma have been investigated. More than 200 times enhancement of $α$ particle emission efficiency (number ratio of escaping $α$ particles and boron nuclei) in plasma has been observed, compared with the cold boron. The proton beam transport path modulated by strong electro-magnetic fields in plasma could dominate the enhanced $α$ particle generation, due to a longer collisional length. In addition, an $α$ particle yield up to 1$\times$10$^{10}$ /sr has been measured via the pitcher-catcher scheme in plasma. This work could benefit understanding of the plasma effects on nuclear reaction dynamics, and also enable opportunities to explore physics in laser fusion associated with advanced fusion fuels.

physics.plasm-ph↗
arXiv2023

Charge equilibration of Laser-accelerated Carbon Ions in Foam Target

The charge equilibration of laser-accelerated carbon ion beams in 2 mg/cm3 foam target was investigated experimentally. The ions were generated through target normal sheath acceleration mechanism in laser-foil interaction scheme. This allows to get the equilibrium charge state in wide energy range near Bragg peak within a single shot. By using foam, the charge equilibration measurement in density regime between gas and solid state was firstly reached out experimentally. It was found that the theoretical predictions with tabulated cross section data for gas target greatly underestimated the charge states. The experimental data are in close agreement with both semi-empirical formula as well as rate equation predictions based on ion-solid interactions. The important role of target density effects that increase the ionization probability and decrease the electron capture probability through frequent multi-collisions in foam are demonstrated. The double electron processes are shown to have little influence on the average charge states. The findings are essential for high energy density physics research where the foams are widely used, and have impacts on a broad range of applications in medical, biological and material fields. The method also provides a new approach to investigate the interaction mechanism of swift heavy ions in matter by taking advantage of the laser-accelerated short-pulse wide-energy range ions.

physics.atom-ph↗
arXiv2023

Characterizing $S$-Artinianness by uniformity

Let $R$ be a commutative ring with identity and $S$ a multiplicative subset of $R$. An $R$-module $M$ is said to be a uniformly $S$-Artinian ($u$-$S$-Artinian for abbreviation) module if there is $s\in S$ such that any descending chain of submodules of $M$ is $S$-stationary with respect to $s$. $u$-$S$-Artinian modules are characterized in terms of ($S$-MIN)-conditions and $u$-$S$-cofinite properties. We call a ring $R$ is a $u$-$S$-Artinian ring if $R$ itself is a $u$-$S$-Artinian module, and then show that any $u$-$S$-semisimple ring is $u$-$S$-Artinian. It is proved that a ring $R$ is $u$-$S$-Artinian if and only if $R$ is $u$-$S$-Noetherian, the $u$-$S$-Jacobson radical ${\rm Jac}_S(R)$ of $R$ is $S$-nilpotent and $R/{\rm Jac}_S(R)$ is a $u$-$S/{\rm Jac}_S(R)$-semisimple ring. Besides, some examples are given to distinguish Artinian rings, $u$-$S$-Artinian rings and $S$-Artinian rings.

math.AC↗
arXiv2023

Proton-Boron Fusion Yield Increased by Orders of Magnitude with Foam Targets

A novel intense beam-driven scheme for high yield of the tri-alpha reaction 11B(p,α)2α was investigated. We used a foam target made of cellulose triacetate (TAC, C_9H_{16}O_8) doped with boron. It was then heated volumetrically by soft X-ray radiation from a laser heated hohlraum and turned into a homogenous, and long living plasma. We employed a picosecond laser pulse to generate a high-intensity energetic proton beam via the well-known Target Normal Sheath Acceleration (TNSA) mechanism. We observed up to 10^{10}/sr α particles per laser shot. This constitutes presently the highest yield value normalized to the laser energy on target. The measured fusion yield per proton exceeds the classical expectation of beam-target reactions by up to four orders of magnitude under high proton intensities. This enhancement is attributed to the strong electric fields and nonequilibrium thermonuclear fusion reactions as a result of the new method. Our approach shows opportunities to pursue ignition of aneutronic fusion.

physics.plasm-ph↗
arXiv2023

Efficient production of nuclear isomer $^{93m}$Mo with laser-accelerated proton beam and an astrophysical implication on $^{92m}$Mo production

Nuclear isomers play a key role in the creation of the elements in the universe and have a number of fascinating potential applications related to the controlled release of nuclear energy on demand. Particularly, $^{93m}$Mo isomer is a good candidate for studying the depletion of nuclear isomer via nuclear excitation by electron capture. For such purposes, efficient approach for $^{93m}$Mo production needs to be explored. In the present work, we demonstrate experimentally an efficient production of $^{93m}$Mo through $^{93}$Nb(p, n) reaction induced by intense laser pulse. When a ps-duration, 100-J laser pulse is employed, the $^{93m}$Mo isomer at 2425 keV (21/2$^+$, $T_{1/2}$ = 6.85 h) are generated with a high yield of $1.8\times10^6$ particles/shot. The resulting peak efficiency is expected to be $10^{17}$ particles/s, which is at least five orders of magnitudes higher than using classical proton accelerator. The effects of production and destruction of $^{93m}$Mo on the controversial astrophysical p-isotope $^{92}$Mo are studied. It is found that the $^{93}$Nb(p, n)-$^{93m}$Mo reaction is an important production path for ^{93m}Mo seed nucleus, and the influence of ^{93m}Mo-^{92}Mo reaction flow on ^{92}Mo production cannot be ignored. In addition, we propose to directly measure the astrophysical rate of (p, n) reaction using laser-induced proton beam since the latter one fits the Maxwell-Boltzmann distribution well. We conclude that laser-induced proton beam opens a new path to produce nuclear isomers with high peak efficiency towards the understanding of p-nuclei nucleosythesis.

nucl-ex↗
arXiv2023

Aharonov-Bohm caging in spin-orbit coupled exciton-polariton lattices

We study the Aharonov-Bohm (AB) caging effect in rhombic exciton-polariton lattices, with the Rashba-Dresselhaus spin-orbit coupling (RDSOC) in acting a synthetic gauge field. The effective magnetic flux through each plaquette is controlled by the orientation of the RDSOC and geometry of the rhombic lattice. The results show that the interplay of lattice geometry and the RDSOC will dramatically influence the energy band structure, furthermore, determining the transportation properties of exciton-polariton condensates. Non-Hermitian effects, which arise from the polariton intrinsic loss mechanism, on the AB caging is also discussed in detail. Meanwhile, the effect of disorder on the dynamics of AB caging is investigated, and we find that the disorder will lead to the inverse Anderson localization. We propose that using the AB caging effect allows to trap and steer the propagation of polaritons in a given parameter regime. Considering the specific example of a photonic liquid crystal microcavity to achieve our theoretical predictions, the AB caging could be switched on and off by applying an external voltage.

cond-mat.quant-gas↗
arXiv2023

Energy loss enhancement of very intense proton beams in dense matter due to the beam-density effect

Thoroughly understanding the transport and energy loss of intense ion beams in dense matter is essential for high-energy-density physics and inertial confinement fusion. Here, we report a stopping power experiment with a high-intensity laser-driven proton beam in cold, dense matter. The measured energy loss is one order of magnitude higher than the expectation of individual particle stopping models. We attribute this finding to the proximity of beam ions to each other, which is usually insignificant for relatively-low-current beams from classical accelerators. The ionization of the cold target by the intense ion beam is important for the stopping power calculation and has been considered using proper ionization cross section data. Final theoretical values agree well with the experimental results. Additionally, we extend the stopping power calculation for intense ion beams to plasma scenario based on Ohm's law. Both the proximity- and the Ohmic effect can enhance the energy loss of intense beams in dense matter, which are also summarized as the beam-density effect. This finding is useful for the stopping power estimation of intense beams and significant to fast ignition fusion driven by intense ion beams.

physics.plasm-ph↗
arXiv2023

On $τ_q$-weak global dimensions of commuative rings

In this paper, the $τ_q$-weak global dimension $τ_q$-\cwd$(R)$ of a commutative ring $R$ is introduced. Rings with $τ_q$-weak global dimension equal to $0$ are studied in terms of homologies, direct products, polynomial extensions and amalgamations. Besides, we investigate the $τ_q$-weak global dimensions of polynomial rings.

math.AC↗
arXiv2023

Some remarks on Lucas modules

In this paper, we discuss some properties on Lucas modules. In details, we show that direct and inverse limits of Lucas modules are Lucas modules, and every $R$-module has a Lucas envelope and a Lucas cover. Moreover, some properties of direct and inverse limits of Lucas modules and some constructions and the unique mapping properties of Lucas envelopes and Lucas covers are investigated.

math.AC↗
arXiv2023

On strongly $ϕ$-$w$-Flat modules and Their Homological Dimensions

In this paper, we introduce and study the notion of strongly $ϕ$-$w$-flat modules. The $ϕ$-$w$-weak global dimension $ϕ$-$w$-w.gl.dim$(R)$ of an NP-ring $R$ is also introduced and studied. We characterize $ϕ$-\Prufer\ $v$-multiplication strongly $ϕ$-rings in terms of strongly $ϕ$-$w$-flat modules.

math.AC↗
arXiv2023

Some Remarks on $ϕ$-Dedekind rings and $ϕ$-Prufer rings

In this paper, the notions of nonnil-injective modules and nonnil-FP-injective modules are introduced and studied. Especially, we show that a $ϕ$-ring $R$ is an integral domain if and only if any nonnil-injective (resp., nonnil-FP-injective) module $R$-module is injective (resp., FP-injective). Some new characterizations of $ϕ$-von Neumann regular rings, nonnil-Notherian rings and nonnil-coherent rings are given. We finally characterize $ϕ$-Dedekind rings and $ϕ$-\Prufer\ rings in terms of $ϕ$-flat modules, nonnil-injective modules and nonnil-FP-injective modules.

math.AC↗
arXiv2022

On $τ_q$-flatness and $τ_q$-coherence

In this paper, we introduce and study the notions of $τ_q$-flat modules and $τ_q$-coheret rings. First, by investigating the Nagata rings of $τ_q$-torsion theory, we show that the small finitistic dimensions of T$(R[x])$ are all equal to $0$ for any ring $R$. Then, we introduce the notion of $τ_q$-VN regular rings (i.e. over which all modules are $τ_q$-flat), and show that a ring $R$ is a $τ_q$-VN regular ring if and only if T$(R[x])$ is a von Neumann regular ring. Finally, we obtain the Chase theorem for $τ_q$-coheret rings: a ring $R$ is $τ_q$-coherent if and only if any direct product of $R$ is $τ_q$-flat if and only if any direct product of flat $R$-modules is $τ_q$-flat. Some examples are provided to compare with the known conceptions.

math.AC↗
arXiv2022

Target density effects on charge tansfer of laser-accelerated carbon ions in dense plasma

We report on charge state measurements of laser-accelerated carbon ions in the energy range of several MeV penetrating a dense partially ionized plasma. The plasma was generated by irradiation of a foam target with laser-induced hohlraum radiation in the soft X-ray regime. We used the tri-cellulose acetate (C$_{9}$H$_{16}$O$_{8}$) foam of 2 mg/cm$^{-3}$ density, and $1$-mm interaction length as target material. This kind of plasma is advantageous for high-precision measurements, due to good uniformity and long lifetime compared to the ion pulse length and the interaction duration. The plasma parameters were diagnosed to be T$_{e}$=17 eV and n$_{e}$=4 $\times$ 10$^{20}$ cm$^{-3}$. The average charge states passing through the plasma were observed to be higher than those predicted by the commonly-used semiempirical formula. Through solving the rate equations, we attribute the enhancement to the target density effects which will increase the ionization rates on one hand and reduce the electron capture rates on the other hand. In previsous measurement with partially ionized plasma from gas discharge and z-pinch to laser direct irradiation, no target density effects were ever demonstrated. For the first time, we were able to experimentally prove that target density effects start to play a significant role in plasma near the critical density of Nd-Glass laser radiation. The finding is important for heavy ion beam driven high energy density physics and fast ignitions.

physics.plasm-ph↗