Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
Phys Rev Lett. 2018 Jul 6;121(1):010402. doi: 10.1103/PhysRevLett.121.010402.
Accelerated charges emit electromagnetic radiation. According to classical electrodynamics, if the charges move along sufficiently close trajectories they emit coherently; i.e., their emitted energy scales quadratically with their number rather than linearly. By investigating the emission by a two-electron wave packet in the presence of an electromagnetic plane wave within strong-field QED, we show that quantum effects deteriorate the coherence predicted by classical electrodynamics even if the typical quantum nonlinearity parameter of the system is much smaller than unity. We explain this result by observing that coherence effects are also controlled by a new quantum parameter which relates the recoil undergone by the electron to the width of its wave packet in momentum space.
加速电荷会发射电磁辐射。根据经典电动力学，如果电荷沿着足够接近的轨迹运动，它们就会相干地发射；也就是说，它们发射的能量与它们的数量成二次方关系，而不是线性关系。通过在强场 QED 中研究电磁平面波存在下的双电子波包的发射，我们表明，即使系统的典型量子非线性参数远小于 1，量子效应对经典电动力学预测的相干性也会产生不利影响。我们通过观察到，相干效应也受到与电子所受反冲与动量空间中其波包宽度相关的新量子参数的控制，从而解释了这一结果。
