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Combined molecular-dynamics and quantum-trajectories simulation of laser-driven, collisional systems
摘要： We introduce a combined molecular-dynamics and quantum-trajectories code to simulate the effects of near-resonant optical fields on state-vector evolution and particle motion in a collisional system. In contrast to collisionless systems, in which the quantum dynamics of multilevel, laser-driven particles with spontaneous emission can be described with the optical Bloch equations (OBEs), particle velocities in sufficiently collisional systems change on timescales comparable to those of the laser-induced, quantum-state dynamics. These transient velocity changes can cause the time-averaged velocity dependence of the quantum state to differ from the OBE solution. We use this multiscale code to describe laser cooling in a strontium ultracold neutral plasma. Important phenomena described by the simulation include suppression of electromagnetically induced transparencies through rapid velocity changing collisions and thermalization between cooled and uncooled directions for anisotropic laser cooling.
关键词： ultracold neutral plasma,molecular-dynamics,laser cooling,collisional systems,quantum-trajectories,laser-driven
更新于2025-09-23 15:19:57
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Bohmian trajectory-bloch wave approach to dynamical simulation of electron diffraction in crystal
摘要： The Bohmian trajectory method is employed to study electron diffraction in crystalline materials. It provides a fresh understanding of the process of electron diffraction, including traveling channels of electrons and formation of diffraction patterns. By combining it with the Bloch wave method, the electron trajectories can be calculated more efficiently than the traditional wave-packet propagation algorithm. Meanwhile, we propose a momentum expectation approach which is a good approximation method with even higher computational efficiency. Both methods result in intuitive and accurate electron trajectories for the simulation of the electron backscatter diffraction (EBSD) pattern. Excellent agreement has been obtained between the simulated trajectory distributions and the experimental EBSD pattern from Mo (001) at 20 kV, where the Kikuchi patterns and higher order Laue zone rings are characterized.
关键词： quantum trajectories,electron diffraction,quantum simulation,Bohmian mechanics
更新于2025-09-09 09:28:46