发表机构
Beijing Normal University; Institute of Applied Physics and Computational Mathematics; Xi’an Jiaotong University; Northwest Normal University（北京师范大学; 应用物理与计算数学研究所; 西安交通大学; 西北师范大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过二维自旋分辨QED-PIC模拟，发现激光与纳米线阵列靶相互作用可产生高电荷（约308 nC）且平均极化度约0.46的正电子束，为强场QED和自旋相关现象研究提供新途径。
AI 中文摘要
研究了线偏振激光脉冲与纳米线阵列靶相互作用中高电荷、高极化正电子束的产生。在此过程中，激光驱动的电子通过非线性康普顿散射（NCS）发射高能光子，随后通过非线性布雷特-惠勒（NBW）过程产生电子-正电子对。我们使用二维自旋分辨量子电动力学粒子模拟（QED-PIC）来模拟这一相互作用。在正电子产生时，$S_z$的符号与局部$B_z$的符号在统计上相关。激光-纳米线相互作用产生的时空场结构增强了产生自旋符号与后续横向洛伦兹冲量方向之间的相关性，从而限制了在给定角度上相反自旋贡献之间的抵消。结果表明，平均极化度达到$|\bar S_z|\approx0.46$，满足$|\bar S_z|>0.3$的正电子电荷约为$308\\,\mathrm{nC}$。参数扫描显示，在中等靶密度和纳米线周期下，高极化正电子电荷达到最大值。这样的源可以用于强场QED的极化敏感研究以及高能和材料物理中的自旋相关现象研究。
英文摘要
The generation of high-charge, highly polarized positron beams in the interaction of a linearly polarized laser pulse with a nanowire-array target is investigated. Here, laser-driven electrons emit high-energy photons through nonlinear Compton scattering (NCS), which subsequently produce electron--positron pairs through the nonlinear Breit--Wheeler (NBW) process. We model this interaction using two-dimensional spin-resolved quantum electrodynamics particle-in-cell (QED-PIC)} simulations. At positron birth, the sign of $S_z$ is statistically correlated with that of the local $B_z$. The spatiotemporal field structure arising from the laser--nanowire interaction strengthens the correlation between the birth spin sign and the direction of the subsequent transverse Lorentz impulse, thereby limiting cancellation between opposite-spin contributions at a given angle. The results show that the average polarization degree reaches $|\bar S_z|\approx0.46$, and the positron charge satisfying $|\bar S_z|>0.3$ is approximately $308\,\mathrm{nC}$. Parameter scans reveal that the high-polarization positron charge is maximized at intermediate target densities and nanowire periods. Such a source could enable polarization-sensitive studies of strong-field QED and spin-dependent phenomena in high-energy and materials physics.
