标题： 引力子物理：引力子的量子场论，引力子噪声和引力退相干——简明教程 显示英文标题

标题： Graviton physics: Quantum field theory of gravitons, graviton noise and gravitational decoherence -- a concise tutorial

摘要： 2015年引力波的探测开启了引力波天文学的新时代，能够深入研究黑洞和中子星的强场动力学。 它为实验室和空间测试爱因斯坦的经典广义相对论理论开辟了一个令人兴奋的新窗口。 近年来有两个有趣的提议旨在揭示微扰引力的量子性质：1）关于宇宙早期引力场真空在暴胀膨胀强烈压缩后产生的引力子噪声的理论预测；2）利用两个处于叠加态质量之间的量子纠缠的实验提议。 第一个提议涉及量子场的随机特性，第二个则涉及量子信息的一个关键概念。 一个同样基本且有趣的想法是询问并探讨引力是否可能使一个量子系统在外观上变得经典，这被称为引力退相干。 由于引力是普遍的，因此由引力引起的退相干特别引人关注。 这是宏观量子现象中的一个重要问题。 要充分理解这些激动人心的发展，需要掌握经典广义相对论、量子场论和量子信息的基本知识，并对随机过程（即量子场中的噪声）有一定的熟悉程度。 传统上，新研究人员可能对这四个学科中的一个或两个有所了解：广义相对论、量子场论、量子信息、随机过程，这取决于他们的背景。 本教程试图在它们之间建立必要的联系，帮助来自这四个学科中的任何一个的读者跃迁到这些跨学科研究主题的前沿。 在这里，我们将处理标题中列出的三个主题，除了引力纠缠，因为其与量子引力相关的性质和影响仍包含许多有争议的元素。 显示英文摘要

摘要： The detection of gravitational waves in 2015 ushered in a new era of gravitational wave astronomy capable of probing into the strong field dynamics of black holes and neutron stars. It has opened up an exciting new window for laboratory and space tests of Einstein's theory of classical general relativity. In recent years there are two interesting proposals aimed at revealing the quantum natures of perturbative gravity: 1) theoretical predictions in how graviton noise from the early universe after the vacuum of the gravitational field was strongly squeezed by inflationary expansion; 2) experimental proposals using the quantum entanglement between two masses each in a superposition state. The first proposal invokes the stochastic properties of quantum fields, the second invokes a key concept of quantum information. An equally basic and interesting idea is to ask whether and how gravity might be responsible for a quantum system becoming classical in appearance, known as gravitational decoherence. Decoherence due to gravity is of special interest because gravity is universal. This is an important issue in macroscopic quantum phenomena. To fully appreciate these exciting developments requires a working knowledge in classical GR, QF theory and QI plus some familiarity with stochastic processes, namely, noise in quantum fields. Traditionally a new researcher may be conversant in one or two of these four subjects: GR, QFT, QI, SP, depending on his/her background. This tutorial attempts to provide the necessary connections between them, helping an engaging reader from any one of these four subjects to leapfrog to the frontier of these interdisciplinary research topics. Here we shall treat the three topics listed in the title, save gravitational entanglement, because its nature and implications proclaimed in relation to quantum gravity still contain many controversial elements.