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We conduct a molecular dynamics simulation of an inelastic gas system utilizing an event-driven algorithm combined with a thermostat mechanism. Initially, the kinetic energy of the system experiences a decay before settling into a…

Computational Physics · Physics 2025-02-03 Rameez Farooq Shah , Shikha Kumari , Syed Rashid Ahmad

We study the dynamics of a one-dimensional Bose gas at unit filling in both shallow and deep optical lattices and obtain the dynamic structure factor ${S(k,\omega)}$ by monitoring the linear response to a weak probe pulse. We introduce a…

Quantum Gases · Physics 2022-08-24 Mathias Gartner , Ferran Mazzanti , Robert E. Zillich

A simple pseudo-Hamiltonian formulation is proposed for the linear inhomogeneous systems of ODEs. In contrast to the usual Hamiltonian mechanics, our approach is based on the use of non-stationary Poisson brackets, i.e. corresponding…

Quantum Physics · Physics 2009-11-11 V. G. Kupriyanov , S. L. Lyakhovich , A. A. Sharapov

Can high energy physics be simulated by low-energy, non-relativistic, many-body systems, such as ultracold atoms? Such ultracold atomic systems lack the type of symmetries and dynamical properties of high energy physics models: in…

Quantum Physics · Physics 2015-12-29 Erez Zohar , J. Ignacio Cirac , Benni Reznik

The interaction of laser fields with solid-state systems can be modeled efficiently within the velocity-gauge formalism of real-time time dependent density functional theory (RT-TDDFT). In this article, we discuss the implementation of the…

Materials Science · Physics 2018-04-04 C. D. Pemmaraju , F. D. Vila , J. J. Kas , S. A. Sato , J. Rehr , K. Yabana , David Prendergast

We investigate gauge invariance against phase space shifting in nonequilibrium systems, as represented by time-dependent many-body Hamiltonians that drive an initial ensemble out of thermal equilibrium. The theory gives rise to gauge…

Statistical Mechanics · Physics 2025-04-25 Johanna Müller , Florian Sammüller , Matthias Schmidt

Methods of quantum nuclear wave-function dynamics have become very efficient in simulating large isolated systems using the time-dependent variational principle (TDVP). However, a straightforward extension of the TDVP to the density matrix…

Chemical Physics · Physics 2015-06-23 Loic Joubert-Doriol , Artur F. Izmaylov

In parallel with the evolution of femtosecond and attosecond laser as well as free-electron laser technology, a variety of theoretical methods have been developed to describe the behavior of atoms, molecules, clusters, and solids under the…

Atomic Physics · Physics 2015-11-12 Kenichi L. Ishikawa , Takeshi Sato

Simulating quantum dynamics of lattice gauge theories (LGTs) is an exciting frontier in quantum science. Programmable quantum simulators based on neutral atom arrays are a promising approach to achieve this goal, since strong Rydberg…

Quantum Physics · Physics 2024-08-07 Johannes Feldmeier , Nishad Maskara , Nazlı Uğur Köylüoğlu , Mikhail D. Lukin

The time-dependent complete-active-space self-consistent-field (TD-CASSCF) method for the description of multielectron dynamics in intense laser fields is presented, and a comprehensive description of the method is given. It introduces the…

Atomic Physics · Physics 2015-06-15 Takeshi Sato , Kenichi L. Ishikawa

An implicit scheme for steady state solutions of diatomic gas flow is presented. The method solves the Rykov model equation in the finite volume discrete velocity method (DVM) framework, in which the translational and rotational degrees of…

Computational Physics · Physics 2018-11-01 Ruifeng Yuan , Chengwen Zhong

We present a new adaptive method for electronic structure calculations based on novel fast algorithms for reduction of multivariate mixtures. In our calculations, spatial orbitals are maintained as Gaussian mixtures whose terms are selected…

Numerical Analysis · Mathematics 2019-06-19 Gregory Beylkin , Lucas Monzon , Xinshuo Yang

Gauge theories are the cornerstone of our understanding of fundamental interactions among particles. Their properties are often probed in dynamical experiments, such as those performed at ion colliders and high-intensity laser facilities.…

We analyze the dynamical equations obeyed by a classical system with position-dependent mass. It is shown that there is a non-conservative force quadratic in the velocity associated to the variable mass. We construct the Lagrangian and the…

Mathematical Physics · Physics 2013-01-18 Sara Cruz y Cruz , Oscar Rosas-Ortiz

Lattice gauge theory has provided a crucial non-perturbative method in studying canonical models in high-energy physics such as quantum chromodynamics. Among other models of lattice gauge theory, the lattice gauge-Higgs model is a quite…

Quantum Gases · Physics 2015-06-08 Yoshihito Kuno , Kenichi Kasamatsu , Yoshiro Takahashi , Ikuo Ichinose , Tetsuo Matsui

We present a grid-based implementation of the time-dependent configuration-interaction singles method suitable for computing the strong-field ionization of small gas-phase molecules. After outlining the general equations of motion used in…

Chemical Physics · Physics 2022-10-19 Stefanos Carlström , Michael Spanner , Serguei Patchkovskii

Gauge theories appear broadly in physics, ranging from the standard model of particle physics to long-wavelength descriptions of topological systems in condensed matter. However, systems with sign problems are largely inaccessible to…

Quantum Physics · Physics 2020-09-24 Di Luo , Jiayu Shen , Michael Highman , Bryan K. Clark , Brian DeMarco , Aida X. El-Khadra , Bryce Gadway

We study the gauge invariance of laser-matter interaction. The velocity gauge where the vector potential is expanded to the $n$-th order with respect to the spatial coordinate, and the length gauge where the electric and magnetic fields are…

Atomic Physics · Physics 2018-12-19 Ryoji Anzaki , Yasushi Shinohara , Takeshi Sato , Kenichi L. Ishikawa

In this work, we present a time-dependent (TD) selected configuration interaction method based on our recently-introduced adaptive configuration interaction (ACI). We show that ACI, in either its ground or excited state formalisms, is…

Chemical Physics · Physics 2020-01-08 Jeffrey B. Schriber , Francesco A. Evangelista

We propose a first-principles time-dependent density functional theoretical (TDDFT) approach in momentum (P) space for quantitative study of electron transport in molecular devices under arbitrary biases. In this approach, the basic…

Mesoscale and Nanoscale Physics · Physics 2009-02-10 Zhongyuan Zhou , Shih-I Chu