固体中激光辅助快电子散射的Floquet密度响应

中文摘要 AI 辅助

我们将Joachain及其合作者最初为激光辅助电子-原子碰撞发展的Bethe-Floquet形式推广到时间周期光场中快电子对多体凝聚态靶的非弹性散射。在弹道-靶相互作用的阶展开下，一般的Floquet-Fourier截面可分离为精确的激光修饰弹道核和靶的矩阵值Floquet密度响应。对于空间结构化或平移非不变系统，后者是双动量Floquet结构因子；其动量对角元定义了动态结构因子的Floquet推广，受厄米性、正定性和求和规则约束。作为一般弹道核的可控实现，对缓慢变化非均匀场的eikonal-Volkov近似给出了靶响应的有限动量分辨率卷积。在均匀场偶极极限下，弹道核简化为Bessel函数边带，截面呈现熟悉的Bethe-Floquet形式。Floquet密度关联函数精确分离为泵浦诱导的相干平均密度与外积和连通涨落。在直线轨迹无反冲极限下，相干、靶弹性扇区定义了弱耦合PINEM振幅；重复的相干插入生成PINEM Bessel阶梯，并给出了将该通道与连通损失组合的明确无双重计数规则。作为工作示例，我们解析计算了金属在Drude和扩散极限下的连通、靶改变截面，恢复了Bessel加权的等离激元损失和扩散梳，以及一个驱动二能级模型，该模型通过Bessel通道干涉表现出非对角Floquet相干性。

英文摘要

We extend the Bethe--Floquet formalism of Joachain and coworkers, originally developed for laser-assisted electron--atom collisions, to inelastic scattering of fast electrons from a many-body condensed-matter target in a time-periodic light field. At first order in the projectile--target interaction, the general Floquet--Fourier cross section separates into exact laser-dressed projectile kernels and a matrix-valued Floquet density response of the target. For spatially structured or translationally non-invariant systems, the latter is the bi-momentum Floquet structure factor; its momentum diagonal defines the Floquet generalization of the dynamic structure factor, constrained by Hermiticity, positivity, and sum rules. As a controlled realization of the general projectile kernel, an eikonal--Volkov approximation for slowly varying inhomogeneous fields yields a finite-momentum-resolution convolution of the target response. In the homogeneous-field dipole limit, the projectile kernel reduces to Bessel-function sidebands and the cross section takes the familiar Bethe--Floquet form. The Floquet density correlator separates exactly into the outer product of the pump-induced coherent mean density and connected fluctuations. In the straight-trajectory nonrecoil limit, the coherent, target-elastic sector defines the weak-coupling PINEM amplitude; repeated coherent insertions generate the PINEM Bessel ladder, with an explicit no-double-counting prescription for combining this channel with connected losses. As worked examples, we evaluate the connected, target-changing cross section analytically for a metal in the Drude and diffusive limits, recovering Bessel-weighted plasmon-loss and diffusive combs, and for a driven two-level model that exhibits off-diagonal Floquet coherences through Bessel-channel interference.

发表机构

• University of Regensburg（雷根斯堡大学）
• Halle-Berlin-Regensburg Cluster of Excellence CCE（哈雷-柏林-雷根斯堡卓越集群）
• Charles University（查理大学）

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