Gómez César, Letschka Raoul, Zell Sebastian
1Instituto de Física Teórica UAM-CSIC, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
2Arnold Sommerfeld Center, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 Munich, Germany.
Eur Phys J C Part Fields. 2018;78(8):610. doi: 10.1140/epjc/s10052-018-6088-2. Epub 2018 Jul 31.
In theories with long-range forces like QED or perturbative gravity, only rates that include emitted soft radiation are non-vanishing. Independently of detector resolution, finite observables can only be obtained after integrating over the IR-component of this radiation. This integration can lead to some loss of quantum coherence. In this note, however, we argue that it should in general not lead to full decoherence. Based on unitarity, we suggest a way to define non-vanishing off-diagonal pieces of the IR-finite density matrix. For this IR-finite density matrix, we estimate the dependence of the loss of quantum coherence, i.e. of its purity, on the scattering kinematics.
在具有长程力的理论中，如量子电动力学（QED）或微扰引力，只有包含发射软辐射的速率才不为零。与探测器分辨率无关，只有在对这种辐射的红外分量进行积分之后，才能获得有限的可观测量。这种积分可能会导致一些量子相干性的损失。然而，在本笔记中，我们认为一般情况下它不应导致完全退相干。基于幺正性，我们提出了一种定义红外有限密度矩阵非零非对角元的方法。对于这个红外有限密度矩阵，我们估计了量子相干性损失（即其纯度）对散射运动学的依赖性。
