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A discretization scheme is introduced for a set of convection-diffusion equations with a non-linear reaction term, where the convection velocity is constant for each reactant. This constancy allows a transformation to new spatial variables,…

Computational Physics · Physics 2017-09-19 József Vass , Sergey N. Krylov

In this paper we study the stability of explicit finite difference discretizations of linear advection-diffusion equations (ADE) with arbitrary order of accuracy in the context of method of lines. The analysis first focuses on the stability…

Numerical Analysis · Mathematics 2020-06-17 Xianyi Zeng , Md Mahmudul Hasan

We report the observation of a quasi-coherent density fluctuation (QCF) by the Doppler backscattering system in the scrape-off layer (SOL) region of the DIII-D tokamak. This QCF is observed in high-power, high-performance hybrid plasmas…

Plasma Physics · Physics 2021-05-21 R. Hong , T. L. Rhodes , Z. Y. Li , H. Wang , L. Zeng , K. Barada , G. Wang , J. G. Watkins , W. A. Peebles

Discrete-variable (DV) quantum key distribution (QKD) based on single-photon detectors and sources have been successfully deployed for long-range secure key distribution. On the other hand, continuous-variable (CV) quantum key distribution…

Quantum Physics · Physics 2024-06-24 Sebastian P. Kish , Patrick J. Gleeson , Angus Walsh , Ping Koy Lam , Syed M. Assad

We propose a frequency-division multiplexed (FDM) continuous-variable quantum key distribution (CV-QKD) system with enhanced spectral efficiency through dense multiplexing of low-symbol-rate signals. A four-channel 10-Mbaud FDM-CV-QKD…

Quantum Physics · Physics 2026-03-24 Jahyeok Han , Donghyeok Le , Minseok Ryu , Syed Assad , Yong-Su Kim , Sunghyun Bae

Motivated by the discrete dipole approximation (DDA) for the scattering of electromagnetic waves by a dielectric obstacle that can be considered as a simple discretization of a Lippmann-Schwinger style volume integral equation for…

Numerical Analysis · Mathematics 2025-08-01 Martin Costabel , Monique Dauge , Khadijeh Nedaiasl

Computational fluid dynamics (CFD) is a specialised branch of fluid mechanics that utilises numerical methods and algorithms to solve and analyze fluid-flow problems. One promising avenue to enhance CFD is the use of quantum computing,…

Quantum Physics · Physics 2025-07-01 Javier Gonzalez-Conde , Dylan Lewis , Sachin S. Bharadwaj , Mikel Sanz

Quantum state diffusion (QSD) as a tool to solve quantum-optical master equations by stochastic simulation can be made several orders of magnitude more efficient if states in Hilbert space are represented in a moving basis of excited…

atom-ph · Physics 2009-10-28 R. Schack , T. A. Brun , I. C. Percival

Diffusion models excel in image generation but are computational and resource-intensive due to their reliance on iterative Markov chain processes, leading to error accumulation and limiting the effectiveness of naive compression techniques.…

Computer Vision and Pattern Recognition · Computer Science 2025-06-23 Beomseok Ko , Hyeryung Jang

Simulation of 3D low-frequency electromagnetic fields propagating in the Earth is computationally expensive. We present a fictitious wave domain high-order finite-difference time-domain (FDTD) modelling method on nonuniform grids to compute…

Numerical Analysis · Mathematics 2023-02-13 Pengliang Yang , Rune Mittet

The timestep of the Finite-Difference Time-Domain method (FDTD) is constrained by the stability limit known as the Courant-Friedrichs-Lewy (CFL) condition. This limit can make FDTD simulations quite time consuming for structures containing…

Computational Engineering, Finance, and Science · Computer Science 2016-06-29 Xihao Li , Costas D. Sarris , Piero Triverio

Diffusion models have achieved remarkable success in generative tasks but suffer from high computational costs due to their iterative sampling process and quadratic attention costs. Existing training-free acceleration strategies that reduce…

Machine Learning · Computer Science 2025-07-24 Ting Jiang , Yixiao Wang , Hancheng Ye , Zishan Shao , Jingwei Sun , Jingyang Zhang , Zekai Chen , Jianyi Zhang , Yiran Chen , Hai Li

This paper develops a quantized Q-learning algorithm for the optimal control of controlled diffusion processes on $\mathbb{R}^d$ under both discounted and ergodic (average) cost criteria. We first establish near-optimality of finite-state…

Optimization and Control · Mathematics 2026-03-16 Erhan Bayraktar , Ali D. Kara , Somnath Pradhan , Serdar Yuksel

A standard approach to solving the S$_N$ transport equations is to use source iteration with diffusion synthetic acceleration (DSA). Although this approach is widely used and effective on many problems, there remain some practical issues…

Numerical Analysis · Mathematics 2020-07-22 Ben S. Southworth , Milan Holec , Terry S. Haut

Text-to-image diffusion models are computationally intensive, often requiring dozens of forward passes through large transformer backbones. For instance, Stable Diffusion XL generates high-quality images with 50 evaluations of a…

Computer Vision and Pattern Recognition · Computer Science 2025-09-03 Natalia Frumkin , Diana Marculescu

In this paper, we consider distributed algorithms for solving the empirical risk minimization problem under the master/worker communication model. We develop a distributed asynchronous quasi-Newton algorithm that can achieve superlinear…

Optimization and Control · Mathematics 2019-06-11 Saeed Soori , Konstantin Mischenko , Aryan Mokhtari , Maryam Mehri Dehnavi , Mert Gurbuzbalaban

Twin-field (TF) quantum key distribution (QKD) fundamentally alters the rate-distance relationship of QKD, offering the scaling of a single-node quantum repeater. Although recent experiments have demonstrated the new opportunities for…

Dropout is a technique that silences the activity of units stochastically while training deep networks to reduce overfitting. Here we introduce Quantal Synaptic Dilution (QSD), a biologically plausible model of dropout regularisation based…

Machine Learning · Computer Science 2020-09-29 Gardave S Bhumbra

Equivocal 3D lesion segmentation exhibits high inter-observer variability. Conventional deterministic models ignore this aleatoric uncertainty, producing over-confident masks that obscure clinical risks. Conversely, while generative methods…

Computer Vision and Pattern Recognition · Computer Science 2026-03-05 Chao Wu , Kangxian Xie , Mingchen Gao

In practical implementation of quantum key distributions (QKD), it requires efficient, real-time feedback control to maintain system stability when facing disturbance from either external environment or imperfect internal components.…

Quantum Physics · Physics 2019-08-07 Jing-Yang Liu , Hua-Jian Ding , Chun-Mei Zhang , Shi-Peng Xie , Qin Wang