Hasil untuk "Physics"

Sifan Wang, Hanwen Wang, P. Perdikaris

Enabling the rapid emulation of parametric differential equations with physics-informed deep operator networks.

A. Browaeys, T. Lahaye

Recent decades have witnessed great developments in the field of quantum simulation—where synthetic systems are built and studied to gain insight into complicated, many-body real-world problems. Systems of individually controlled neutral atoms, interacting with each other when excited to Rydberg states, have emerged as a promising platform for this task, particularly for the simulation of spin systems. Here, we review the techniques necessary for the manipulation of neutral atoms for the purpose of quantum simulation—such as quantum gas microscopes and arrays of optical tweezers—and explain how the different types of interactions between Rydberg atoms allow a natural mapping onto various quantum spin models. We discuss recent achievements in the study of quantum many-body physics in this platform, and some current research directions beyond that. This Review Article outlines the techniques necessary for the manipulation of neutral atoms and making use of their interactions, when excited to Rydberg states, to achieve the goal of quantum simulation of many-body physics.

R. El-Ganainy, K. Makris, M. Khajavikhan et al.

M. Nakahara

Hang Su, Dong Zhao, Ali Asghar Heidari et al.

Kristian Kirsch

A. Fridman, L. Kennedy

PART 1. FUNDAMENTALS OF PLASMA PHYSICS AND PLASMA CHEMISTRY. CHAPTER 1. Introduction CHAPTER 2. ELEMENTARY PROCESSES OF CHARGED SPECIES IN PLASMA. 2.1. Elementary Charged Particles In Plasma, And Their Elastic And Inelastic Collisions. 2.2. Ionization Processes. 2.3. Mechanisms Of Electron Losses: The Electron-Ion Recombination. 2.4. The Electron Losses Due To Formation Of Negative Ions: Electron Attachment And Detachment Processes. 2.5. The Ion-Ion Recombination Processes. 2.6. The Ion-Molecular Reactions. 2.7. Problems and Concept Questions. CHAPTER 3. ELEMENTARY PROCESSES OF EXCITED MOLECULES AND ATOMS IN PLASMA. 3.1. Electronically Excited Atoms And Molecules In Plasma. 3.2. Vibrationally And Rotationally Excited Molecules. 3.3. Elementary Processes Of Vibrational, Rotational And Electronic Excitation Of Molecules In Plasma. 3.4. Vibrational (VT) Relaxation, Landau-Teller Formula. 3.5. Vibrational Energy Transfer Between Molecules, VV-Relaxation Processes. 3.6. Processes Of Rotational And Electronic Relaxation Of Excited Molecules. 3.7. Elementary Chemical Reactions Of Excited Molecules, Fridman - Macheret a-Model. 3.8. Problems and Concept Questions. CHAPTER 4. PLASMA STATISTICS AND KINETICS OF CHARGED PARTICLES. 4.1. Statistics And Thermodynamics Of Equilibrium And Non-Equilibrium Plasmas, The Boltzmann, Saha And Treanor Distributions. 4.2. The Boltzmann And Fokker-Planck Kinetic Equations, Electron Energy Distribution Functions. 4.3. Electric And Thermal Conductivity In Plasma, Diffusion Of Charged Particles. 4.4. Breakdown Phenomena: The Townsend And Spark Mechanisms, Avalanches, Streamers And Leaders. 4.5. Steady-State Regimes Of Non-Equilibrium Electric Discharges. 4.6. Problems and Concept Questions. CHAPTER 5. KINETICS OF EXCITED PARTICLES IN PLASMA. 5.1.Vibrational Distribution Functions In Non-Equilibrium Plasma, The Fokker-Planck Kinetic Equation. 5.2. Non-Equilibrium Vibrational Kinetics: eV-Processes, Polyatomic Molecules, Non-Steady-State Regimes. 5.3. Macrokinetics Of Chemical Reactions And Relaxation Of Vibrationally Excited Molecules. 5.4. Vibrational Kinetics In Gas Mixtures, Isotopic Effect In Plasma Chemistry. 5.5. Kinetics Of Electronically And Rotationally Excited States, Non-Equilibrium Translational Distributions, Relaxation And Reactions Of Hot Atoms In Plasma. 5.6. Energy Efficiency, Energy Balance And Macrokinetics Of Plasma-Chemical Processes. 5.7. Energy Efficiency Of Quasi-Equilibrium Plasma-Chemical Systems, Absolute, Ideal And Super-Ideal Quenching. 5.8. Problems and Concept Questions. CHAPTER 6. ELECTROSTATICS, ELECTRODYNAMICS AND FLUID MECHANICS OF PLASMA. 6.1. Electrostatic Plasma Phenomena: Debye-Radius And Sheaths, Plasma Oscillations And Plasma Frequency. 6.2. Magneto-Hydrodynamics Of Plasma. 6.3. Instabilities Of Low Temperature Plasma. 6.4. Non-Thermal Plasma Fluid Mechanics In Fast Subsonic And Supersonic Flows. 6.5. Electrostatic, Magneto-Hydrodynamic And Acoustic Waves In Plasma. 6.6. Propagation Of Electro-Magnetic Waves In Plasma. 6.7. Emission And Absorption Of Radiation In Plasma, Continuous Spectrum. 6.8. Spectral Line Radiation In Plasma. 6.9. Non-Linear Phenomena In Plasma. 6.10. Problems and Concept Questions. PART 2. PHYSICS AND ENGINEERING OF ELECTRIC DISCHARGES. CHAPTER 7. GLOW DISCHARGE. 7.1. Structure And Physical Parameters Of Glow Discharge Plasma. Current-Voltage Characteristics, Comparison Of Glow And Dark Discharges. 7.2. Cathode And Anode Layers Of A Glow Discharge. 7.3. Positive Column Of Glow Discharge. 7.4. Glow Discharge Instabilities. 7.5. Different Specific Glow Discharge Plasma Sources. 7.6. Problems and Concept Questions. CHAPTER 8. ARC DISCHARGES. 8.1. Physical Features, Types, Parameters And Current-Voltage Characteristics Of Arc Discharges. 8.2. Mechanisms Of Electron Emission From Cathode. 8.3. Cathode And Anode Layers In Arc Discharges. 8.4. Positive Column Of Arc Discharges. 8.5. Different Configurations Of Arc Discharges. 8.6. Gliding Arc Discharge. 8.7. Problems and Concept Questions. CHAPTER 9. NON-EQUILIBRIUM COLD ATMOSPHERIC PRESSURE PLASMAS: CORONA, DIELECTRIC BARRIER AND SPARK DISCHARGES. 9.1. The Continuous Corona Discharge. 9.2. The Pulsed Corona Discharge. 9.3. Dielectric-Barrier Discharge. 9.4. Spark Discharges. 9.5. Problems and Concept Questions. CHAPTER 10. PLASMA CREATED IN HIGH FREQUENCY ELECTROMAGNETIC FIELDS: RADIO-FREQUENCY (RF), MICROWAVE AND OPTICAL DISCHARGES. 10.1. Radio-Frequency (RF) Discharges At High Pressures, Inductively Coupled Thermal RF Discharges. 10.2. Thermal Plasma Generation In Microwave And Optical Discharges. 10.3. Non-Equilibrium Radio-Frequency (RF) Discharges, General Features Of Non-Thermal Capacitively-Coupled (CCP) Discharges. 10.4. Non-Thermal Capacitively-Coupled (CCP) Discharges Of Moderate Pressure. 10.5. Low Pressure Capacitively-Coupled RF Discharges. 10.6. Asymmetric, Magnetron And Other Special Forms Of Low Pressure Capacitive RF-Discharges. 10.7. Non-Thermal Inductively-Coupled (ICP) Discharges. 10.8. Non-Thermal Low-Pressure Microwave And Other Wave-Heated Discharges. 10.9. Non-Equilibrium Microwave Discharges Of Moderate-Pressure. 10.10. Problems and Concept Questions. CHAPTER 11. DISCHARGES IN AEROSOLS, DUSTY PLASMAS. 11.1. Photo-Ionization Of Aerosols. 11.2.Thermal Ionization Of Aerosols. 11.3. Electric Breakdown Of Aerosols. 11.4. Steady-State Dc Electric Discharge In Heterogeneous Medium. 11.5. Dusty Plasma Formation, Evolution Of Nano-Particles In Plasma. 11.6. Critical Phenomena In Dusty Plasma Kinetics. 11.7. Non-Equilibrium Clusterization In Centrifugal Field. 11.8. Dusty Plasma Structures: Phase Transitions, Coulomb Crystals, Special Oscillations. 11.9. Problems and Concept Questions. CHAPTER 12. ELECTRON BEAM PLASMAS. 12.1.Generation And Properties Of Electron-Beam Plasmas. 12.2. Kinetics Of Degradation Processes, Degradation Spectrum. 12.3. Plasma-Beam Discharge. 12.4. Non-Equilibrium High-Pressure Discharges Sustained By High-Energy Electron Beams. 12.5. Plasma In Tracks Of Nuclear Fission Fragments, Plasma Radiolysis. 12.6. Dusty Plasma Generation By A Relativistic Electron Beam. 12.7. Problems and Concept Questions.

Di Xiao, Gui-Bin Liu, W. Feng et al.

We show that inversion symmetry breaking together with spin-orbit coupling leads to coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides, making possible controls of spin and valley in these 2D materials. The spin-valley coupling at the valence-band edges suppresses spin and valley relaxation, as flip of each index alone is forbidden by the valley-contrasting spin splitting. Valley Hall and spin Hall effects coexist in both electron-doped and hole-doped systems. Optical interband transitions have frequency-dependent polarization selection rules which allow selective photoexcitation of carriers with various combination of valley and spin indices. Photoinduced spin Hall and valley Hall effects can generate long lived spin and valley accumulations on sample boundaries. The physics discussed here provides a route towards the integration of valleytronics and spintronics in multivalley materials with strong spin-orbit coupling and inversion symmetry breaking.

M. Bähr, S. Gieseke, M. Gigg et al.

AbstractIn this paper we describe $\mathsf{Herwig++}$ version 2.2, a general-purpose Monte Carlo event generator for the simulation of hard lepton-lepton and hadron-hadron collisions. A number of important hard scattering processes are available, together with an interface via the Les Houches Accord to specialized matrix element generators for additional processes. The simulation of Beyond the Standard Model (BSM) physics includes a range of models and allows new models to be added by encoding the Feynman rules of the model. The parton-shower approach is used to simulate initial- and final-state QCD radiation, including colour coherence effects, with special emphasis on the correct description of radiation from heavy particles. The underlying event is simulated using an eikonal multiple parton-parton scattering model. The formation of hadrons from the quarks and gluons produced in the parton shower is described using the cluster hadronization model. Hadron decays are simulated using matrix elements, where possible including spin correlations and off-shell effects.

C. Castellano, S. Fortunato, V. Loreto

Statistical physics has proven to be a fruitful framework to describe phenomena outside the realm of traditional physics. Recent years have witnessed an attempt by physicists to study collective phenomena emerging from the interactions of individuals as elementary units in social structures. A wide list of topics are reviewed ranging from opinion and cultural and language dynamics to crowd behavior, hierarchy formation, human dynamics, and social spreading. The connections between these problems and other, more traditional, topics of statistical physics are highlighted. Comparison of model results with empirical data from social systems are also emphasized.

R. C. Weast

S. Chandrasekhar

J. Peixoto, A. Oort

Iu. P. Raizer

R. Courant, D. Hilbert

T. Squires, S. Quake

G. Mahan

L. Spitzer

P. McMahon

Optical computing has the potential to be faster and more energy-efficient than conventional digital-electronic computing for certain applications. This Perspective article surveys the differences between optics and electronics that could be exploited, and explores the physics and engineering challenges in realizing useful optical computers. There has been a resurgence of interest in optical computing since the early 2010s, both in academia and in industry, with much of the excitement centred around special-purpose optical computers for neural-network processing. Optical computing has been a topic of periodic study since the 1960s, including for neural networks in the 1980s and early 1990s, and a wide variety of optical-computing schemes and architectures have been proposed. In this Perspective article, we provide a systematic explanation of why and how optics might be able to give speed or energy-efficiency benefits over electronics for computing, enumerating 11 features of optics that can be harnessed when designing an optical computer. One often-mentioned motivation for optical computing — that the speed of light is fast — is emphatically not a key differentiating physical property of optics for computing; understanding where an advantage could come from is more subtle. We discuss how gaining an advantage over state-of-the-art electronic processors will likely only be achievable by careful design that harnesses more than 1 of the 11 features, while avoiding a number of pitfalls that we describe.