The Functional Schrodinger Equation in the Semiclassical Limit of Quantum Gravity with a Gaussian Clock Field

平坦时空和德西特时空中的反作用包含施温格效应：基于自洽麦克斯韦-薛定谔半经典动力学

Backreaction inclusive Schwinger effect in flat and de Sitter spacetimes via a self consistent Maxwell Schrodinger semiclassical dynamics

该研究用自洽半经典框架研究平坦和德西特时空中施温格效应的反作用，发现反作用导致电场和电流的等离子体样振荡及模占据数振荡，但不增加不可逆粒子产生。

Semiclassical cosmology with back reaction: the Friedmann-Schrodinger equation and inflation

We propose and study a semi-classical cosmological system akin to the Newton-Schrödinger equation where matter field evolution is determined by time dependent Schrödinger equation. The resulting dynamics is one where the scale factor self-consistently informs the quantum evolution of the scalar field wave function via the Friedmann equation. We study various potentials, and show that for each case, inflation arises naturally, without fine-tuning, for arbitrary initial wave functions for the scalar field. Furthermore, due to zero-point quantum fluctuations of the scalar field, the equation of s…

更健康的随机半经典引力：没有薛定谔猫的世界

A healthier stochastic semiclassical gravity: world without Schrödinger cats

针对半经典引力平均场耦合的缺陷，提出基于自发量子监测与反馈的混合经典-量子耦合方法，消除薛定谔猫态、纳入涨落并恢复线性，但相对论化仍受量子基础限制。

德西特空间可观测量代数上的半经典态与时间反演对称性

Semiclassical state on algebra of observables for de Sitter space and time reversal symmetry

本文针对德西特静态片全息中迹态无法重现半经典体关联函数的问题，引入重时钟态构造，结合时间反演对称性，推导观测者哈密顿量，为观测者模型提供场论基础。

交叉积与量子参考系：论引力熵的观察者依赖性

Crossed products and quantum reference frames: on the observer-dependence of gravitational entropy

本文利用视角中性QRF形式研究引力熵的观察者依赖性，将交叉积构造推广到任意多个可能简并且与场纠缠的时钟，并在半经典与反半经典区域中给出熵修正及四个明确例子。

量子引力的半经典近似

The semiclassical approximation to quantum gravity

本文对正则框架下量子引力的半经典近似作了较详细的评述。这包括特别是推导功能薛定谔方程和讨论半经典时间以及推导量子引力修正项的薛定谔方程。这些项被用来计算De~Sitter空间中场的能量移动和黑洞蒸发中的非么正贡献。重点也放在退相干的相关性和半经典引力的相关性。在这个框架下，还讨论了非引力量子场在半经典背景下的反作用以及超空间上Berry联系的出现。

Quantizing time: Interacting clocks and systems

This article generalizes the conditional probability interpretation of time in which time evolution is realized through entanglement between a clock and a system of interest. This formalism is based upon conditioning a solution to the Wheeler-DeWitt equation on a subsystem of the Universe, serving as a clock, being in a state corresponding to a time $t$. Doing so assigns a conditional state to the rest of the Universe $|ψ_S(t)\rangle$, referred to as the system. We demonstrate that when the total Hamiltonian appearing in the Wheeler-DeWitt equation contains an interaction term coupling the clo…

相对论和非相对论标量量子力学和量子宇宙学中的精确半经典演化

Exact Semiclassical Evolutions in Relativistic and Nonrelativistic Scalar Quantum Mechanics and Quantum Cosmology

得到了薛定谔方程和克莱因-戈登方程解的半经典近似精确的充要条件。结果表明，存在一个精确的半经典解的薛定谔方程确定半经典波函数和相互作用势唯一的边界条件的选择。这个结果也适用于Klein-Gordon方程。讨论了它对求解FRW标量场小超空间模型的Wheeler-DeWitt方程的意义。特别地，构造了无质量标量场和指数物质势情形下Wheeler-DeWitt方程的精确半经典解。分析了$λϕ^{2p}$形式的多项式物质势的精确半经典解的存在性。结果表明，当p=1，2，3时，不存在右向半经典解.本文还发展了一个与传统的$\hbar$和$M_p^{-1}$ -展开式完全不同的广义半经典微扰展开式。

Qubit clock in quantum cosmology

We investigate the emergent time scenario in quantum cosmology based on the Page-Wotters approach. Using a quantum cosmological model with a qubit clock, it is demonstrated how the entanglement between the qubit clock and the geometry derives emergence of a time parameter which defines evolution of the timeless quantum state of the universe. We show the universe wave function conditioned by a qubit clock obeys the standard Schrödinger equation and the Fisher information for the clock state, which quantifies entanglement between the universe and the clock, contributes as a negative energy densi…

Relativistic quantum clocks

The conflict between quantum theory and the theory of relativity is exemplified in their treatment of time. We examine the ways in which their conceptions differ, and describe a semiclassical clock model combining elements of both theories. The results obtained with this clock model in flat spacetime are reviewed, and the problem of generalizing the model to curved spacetime is discussed, before briefly describing an experimental setup which could be used to test of the model. Taking an operationalist view, where time is that which is measured by a clock, we discuss the conclusions that can be…

Quantum and classical effects in a light-clock falling in Schwarzschild geometry

Quantum theory and relativity offer different conceptions of time. To explore the conflict between them, we study a quantum version of the light-clock commonly used to illustrate relativistic time dilation. This semiclassical model combines elements of both theories. We show for Gaussian states of the light field that the clock time is independent of the initial state. We calculate the discrepancy between two such clocks when one is held in a gravitational field and the other is left to fall a certain distance. Contrasting our results with the case of pointlike observers in general relativity,…

牛顿-薛定谔方程不能从广义相对论+量子场论导出

Newton-Schrödinger Equations are not derivable from General Relativity + Quantum Field Theory

本文从两个方面证明了牛顿-薛定谔方程（NSEs）[arXiv：1210.0457及其参考文献]不符合广义相对论（GR）和量子场论（QFT）：（1）取相对论半经典引力的中心方程--半经典爱因斯坦方程的非相对论极限，这是一个基于GR+QFT的全协变理论，其中量子物质对时空动力学的自洽反作用; 2）建立一个模型[见C。Anastopoulos和B. L.胡同学定量重力30，165007（2013），arXiv：1305.5231]与物质标量场与弱引力相互作用，在程序类似于量子电动力学的非相对论极限的推导。我们的结论是，经典引力与量子物质的耦合只能通过平均场，不存在$N$ -粒子NSE，基于牛顿-薛定谔方程的理论假设未知的物理。