Hasil untuk "Physics"

Alvaro Sanchez-Gonzalez, Jonathan Godwin, T. Pfaff et al.

Here we present a machine learning framework and model implementation that can learn to simulate a wide variety of challenging physical domains, involving fluids, rigid solids, and deformable materials interacting with one another. Our framework---which we term "Graph Network-based Simulators" (GNS)---represents the state of a physical system with particles, expressed as nodes in a graph, and computes dynamics via learned message-passing. Our results show that our model can generalize from single-timestep predictions with thousands of particles during training, to different initial conditions, thousands of timesteps, and at least an order of magnitude more particles at test time. Our model was robust to hyperparameter choices across various evaluation metrics: the main determinants of long-term performance were the number of message-passing steps, and mitigating the accumulation of error by corrupting the training data with noise. Our GNS framework advances the state-of-the-art in learned physical simulation, and holds promise for solving a wide range of complex forward and inverse problems.

Yuto Ashida, Z. Gong, Masahito Ueda

A review is given on the foundations and applications of non-Hermitian classical and quantum physics. First, key theorems and central concepts in non-Hermitian linear algebra, including Jordan normal form, biorthogonality, exceptional points, pseudo-Hermiticity, and parity-time symmetry, are delineated in a pedagogical and mathematically coherent manner. Building on these, we provide an overview of how diverse classical systems, ranging from photonics, mechanics, electrical circuits, and acoustics to active matter, can be used to simulate non-Hermitian wave physics. In particular, we discuss rich and unique phenomena found therein, such as unidirectional invisibility, enhanced sensitivity, topological energy transfer, coherent perfect absorption, single-mode lasing, and robust biological transport. We then explain in detail how non-Hermitian operators emerge as an effective description of open quantum systems on the basis of the Feshbach projection approach and the quantum trajectory approach. We discuss their applications to physical systems relevant to a variety of fields, including atomic, molecular and optical physics, mesoscopic physics, and nuclear physics with emphasis on prominent phenomena and subjects in quantum regimes, such as quantum resonances, superradiance, the continuous quantum Zeno effect, quantum critical phenomena, Dirac spectra in quantum chromodynamics, and nonunitary conformal field theories. Finally, we introduce the notion of band topology in complex spectra of non-Hermitian systems and present their classifications by providing the proof, first given by this review in a complete manner, as well as a number of instructive examples. Other topics related to non-Hermitian physics, including nonreciprocal transport, speed limits, nonunitary quantum walk, are also reviewed.

R. Sharma, D. Rawal

R. Fitzpatrick

: TAE Technologies, Inc. (TAE) is dedicated to the advancement of fusion power by pursuing an alternative approach to magnetic confinement fusion: a neutral-beam driven, field-reversed configuration (FRC). FRCs are high-beta, compact toroid with no toroidal magnetic field. The geometric and magnetic simplicity of the configuration offers a promising path to clean, safe, and economically viable fusion. The central focus of TAE's experimental program is the C-2W experiment, the world's largest FRC device. This fourth-generation device was designed to achieve a set of milestones, namely the sustainment of the FRC for extended durations, the resilience of the FRC against disruptive MHD modes, and the demonstration of heating by neutral beam injection. Through systematic experimentation, C-2W has accomplished its milestones. C-2W's success is attributed to its advanced systems, including modular neutral beam injectors, edge biasing of open field lines for stabilization and enhanced electron confinement, and a real-time plasma control system for precise plasma manipulation. This presentation provides an overview of the C-2W experiment and highlights the continued advancements in performance and evolving understanding of FRC physics.

K. Hagiwara, K. Hikasa, Kei Nakamura et al.

H. Lai, M. Guzzi, J. Huston et al.

We extract new parton distribution functions (PDFs) of the proton by global analysis of hard scattering data in the general-mass framework of perturbative quantum chromodynamics. Our analysis includes new theoretical developments together with the most recent collider data from deep-inelastic scattering, vector boson production, and single-inclusive jet production. Because of the difficulty in fitting both the D0 Run-II W lepton asymmetry data and some fixed-target DIS data, we present two families of PDFs, CT10 and CT10W, without and with these high-luminosity W lepton asymmetry data included in the global analysis. With both sets of PDFs, we study theoretical predictions and uncertainties for a diverse selection of processes at the Fermilab Tevatron and the CERN Large Hadron Collider.

I. Bloch, J. Dalibard, W. Zwerger

This paper reviews recent experimental and theoretical progress concerning many-body phenomena in dilute, ultracold gases. It focuses on effects beyond standard weak-coupling descriptions, such as the Mott-Hubbard transition in optical lattices, strongly interacting gases in one and two dimensions, or lowest-Landau-level physics in quasi-two-dimensional gases in fast rotation. Strong correlations in fermionic gases are discussed in optical lattices or near-Feshbach resonances in the BCS-BEC crossover.

Robert B. Leighton

F. Reif, S. Rice

M. Reed

G. Adomian

W. Richtering

A. Alam, W. Anderson, S. Banerjee et al.

G. Mavko, T. Mukerji, J. Dvorkin

Responding to the latest developments in rock physics research, this popular reference book has been thoroughly updated while retaining its comprehensive coverage of the fundamental theory, concepts, and laboratory results. It brings together the vast literature from the field to address the relationships between geophysical observations and the underlying physical properties of Earth materials - including water, hydrocarbons, gases, minerals, rocks, ice, magma and methane hydrates. This third edition includes expanded coverage of topics such as effective medium models, viscoelasticity, attenuation, anisotropy, electrical-elastic cross relations, and highlights applications in unconventional reservoirs. Appendices have been enhanced with new materials and properties, while worked examples (supplemented by online datasets and MATLAB® codes) enable readers to implement the workflows and models in practice. This significantly revised edition will continue to be the go-to reference for students and researchers interested in rock physics, near-surface geophysics, seismology, and professionals in the oil and gas industries.

W. Magnus, F. Oberhettinger, R. P. Soni et al.

M. Chi, P. Feltovich, R. Glaser

P. Morse, H. Feshbach

P. Rennert

L. Treloar, Clarendon PRESS•OXFORD

K. Vahala