标题： 暗场方法测量真空双折射和光-光耦合——一项原理验证实验 显示英文标题

标题： The Darkfield Approach to Measuring Vacuum Birefringence and Light-by-Light Couplings -- A Proof-of-Principle Experiment

摘要： 真空涨落导致电磁场之间产生有效的非线性相互作用。 这些相互作用通常会改变穿过强场区域的光的特性。 由于其亮度、精确控制的可能性以及有利的频率标度，X射线自由电子激光器构成了一种特别有前景的探测工具。 然而，即使使用XFEL辐射探测紧密聚焦的高强度激光场时，非线性真空响应也非常小，并且至今无法直接测量真正光子的光-光散射以及量子真空相关的基础物理常数。 实现足够好的信噪分离是成功开展量子真空实验的关键。 为了应对这一挑战，最近提出了一种暗场探测概念。 在这里，我们展示了在欧洲X射线自由电子激光高能量密度科学仪器上验证该方法的原理实验结果。 显示英文摘要

摘要： Vacuum fluctuations give rise to effective nonlinear interactions between electromagnetic fields. These generically modify the characteristics of light traversing a strong-field region. X-ray free-electron lasers constitute a particularly promising probe, due to their brilliance, the possibility of precise control and favourable frequency scaling. However, the nonlinear vacuum response is very small even when probing a tightly focused high-intensity laser field with XFEL radiation and direct measurement of light-by-light scattering of real photons and the associated fundamental physics constants of the quantum vacuum has not been possible to date. Achieving a sufficiently good signal-to-background separation is key to a successful quantum vacuum experiment. To master this challenge, a darkfield detection concept has recently been proposed. Here we present the results of a proof-of-principle experiment validating this approach at the High Energy Density scientific instrument of the European X-Ray Free Electron Laser.