- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Theories of Molecular Optical Spectra and Chemical Transformations: Algorithm for ab initio Calculation of the Probabilities of Chemical Reactions Using a Multiminimum Gaussian Potential
摘要： The possibility of formulating and solving the problem of chemical reaction probabilities as a problem of the molecular energy levels and their transition probabilities is considered. The features of using multiminimum Gaussian potentials in such problems are discussed. An algorithm for ab initio calculation of the chemical transformation probabilities with given initial conditions and a list of structures participating in the process is proposed. It is shown that the algorithm can be constructed using a variational procedure with basis functions corresponding to solutions of both one-dimensional problems with a multiminimum potential and problems for each well separately.
关键词： Gaussian function,molecular spectrum,chemical reaction,quantum theory of molecules
更新于2025-09-23 15:21:01
-
Parity–Time Symmetry Synthetic Lasers: Physics and Devices
摘要： The invention of the laser has revolutionized modern science and engineering as well as our daily lives. Recently, a new class of lasers based on concepts borrowed from parity–time symmetry in quantum mechanics has emerged. Parity–time symmetry, initially applied to condensed matter systems, extends canonical quantum theory to non-Hermitian quantum theory. The experimental exploration of parity–time symmetry in electronics is challenging; so by analogy, such concept is introduced in photonics where flexibility exists in realizing non-Hermitian eigenstates involving optical gain and loss. Lasers intrinsically involve both gain and loss, which makes them the natural candidates to explore and exploit parity–time symmetry in photonics. Recent studies have demonstrated various novel laser devices based on parity–time symmetry, which show unique properties such as single mode lasing, chiral mode lasing, and exceptional point enhanced sensing. In this review, the fundamentals are introduced and recent advances in parity–time symmetric laser devices are discussed, furthermore an outlook on this emergent field is provided.
关键词： lasers,exceptional point,photonics,non-Hermitian quantum theory,parity–time symmetry
更新于2025-09-11 14:15:04
-
A High-Performance InAs/GaSb Core-Shell Nanowire Line-Tunneling TFET: An Atomistic Mode-Space NEGF Study
摘要： Using a tight-binding mode-space NEGF technique, we explore the essential physics, design and performance potential of the III-V core-shell (CS) nanowire (NW) heterojunction TFET. The CS TFET “line-tunneling” current increases significantly with the core diameter dC and outperforms the best III-V axial “point-tunneling” NW heterojunction TFET ION by up to 6× for dC = 6.6 nm. Reaching such a high level of current at low supply voltage, however, requires and involves specific and sometime unanticipated optimizations and physics that are thoroughly investigated here. In spite of the commonly accepted view, we also show and explain the weak gate-length dependency observed for the line-tunneling current in a III-V TFET. We further investigate the effect of electron-phonon scattering and discrete dopant impurity band tails on optimized CS NW TFETs. Including those non-idealities, the CS-TFET inverter performance significantly outperforms that of the axial TFETs. The low-power (LP) VDD = 0.35V CS-inverter delay is comparable to that of the high-performance (HP) Si CMOS using VDD = 0.55V, which shows promise for a LP TFET technology with HP speed.
关键词： Semiconductor device modeling,Quantum effect semiconductor devices,Semiconductor heterojunctions,Tunnel transistors,Quantum wires,Quantum theory
更新于2025-09-10 09:29:36
-
Direct interaction along light cones at the quantum level
摘要： Here, we point out that interactions with time delay can be described at the quantum level using a multi-time wave function ψ(x1, ..., xN), i.e. a wave function depending on one spacetime variable xi = (ti, xi) per particle. In particular, such a wave function makes it possible to implement direct interaction along light cones (not mediated by fields), as in the Wheeler–Feynman formulation of electrodynamics. Our results are as follows. (1) We derive a covariant two-particle integral equation and discuss it in detail. (2) It is shown how this integral equation (or equivalently, a system of two integro-differential equations) can be understood as defining the time evolution of ψ in a consistent way. (3) We demonstrate that the equation has strong analogies with Wheeler–Feynman electrodynamics and therefore suggests a possible new quantization of that theory. (4) We propose two natural ways how the two-particle equation can be extended to N particles. It is shown that exactly one of them leads to the usual Schr?dinger equation with Coulomb-type pair potentials if time delay effects are neglected.
关键词： quantization of Wheeler–Feynman electrodynamics,integral equations,relativistic quantum theory,integro-differential equations,interaction with time delay,multi-time wave functions,Bethe–Salpeter equation
更新于2025-09-09 09:28:46
-
Resonant inelastic scattering of two x-ray photons by a many-electron atom
摘要： A nonrelativistic variant of the quantum theory for the resonant inelastic-scattering process of two x-ray photons in the deep 1s-shell ionization threshold energy region of a free many-electron atom is established. A quantitative estimate for the magnitude of the observed differential cross section is given.
关键词： differential cross section,quantum theory,resonant inelastic scattering,many-electron atom,x-ray photons
更新于2025-09-04 15:30:14