The creation of delocalized coherent superpositions of quantum systems experiencing different relativistic effects is an important milestone in future research at the interface of gravity and quantum mechanics. This could be achieved by generating a superposition of quantum clocks that follow paths with different gravitational time dilation and investigating the consequences on the interference signal when they are eventually recombined. Light-pulse atom interferometry with elements employed in optical atomic clocks is a promising candidate for that purpose, but suffers from major challenges including its insensitivity to the gravitational redshift in a uniform field. All these difficulties can be overcome with a novel scheme presented here which is based on initializing the clock when the spatially separate superposition has already been generated and performing a doubly differential measurement where the differential phase shift between the two internal states is compared for different initialization times. This can be exploited to test the universality of the gravitational redshift (UGR) with delocalized coherent superpositions of quantum clocks and it is argued that its experimental implementation should be feasible with a new generation of 10-meter atomic fountains that will soon become available. Interestingly, the approach also offers significant advantages for more compact set-ups based on guided interferometry or hybrid configurations. Furthermore, in order to provide a solid foundation for the analysis of the various interferometry schemes and the effects that can be measured with them, a general formalism for a relativistic description of atom interferometry in curved spacetime is developed. It can deal with freely falling atoms, but also include the effects of external forces and guiding potentials, and can be applied to a very wide range of situations. As an important ingredient for quantum-clock interferometry, suitable diffraction mechanisms for atoms in internal-state superpositions are investigated too. Finally, the relation of the proposed doubly-differential measurement scheme to other experimental approaches and to tests of the universality of free fall (UFF) is discussed in detail.

中文翻译：

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量子时钟干涉法中的引力红移

经历不同相对论效应的量子系统的离域相干叠加的创建是在重力和量子力学的界面上进行未来研究的重要里程碑。这可以通过生成遵循不同引力时间膨胀路径的量子时钟叠加，并研究最终重新组合时对干扰信号的影响来实现。具有用于光原子钟的元件的光脉冲原子干涉仪是用于该目的的有前途的候选者，但是遭受主要挑战，包括其对均匀场中的重力红移不敏感。所有这些困难都可以通过此处提出的新颖方案来克服，该方案基于在已经生成空间上分离的叠加时初始化时钟并执行双重差分测量，其中比较两个内部状态之间的差分相移针对不同的初始化时间。可以利用它来测试引力红移（UGR）与量子时钟的离域相干叠加的普遍性，并认为其实验实现对于不久将可用的新一代10米原子喷泉应该是可行的。有趣的是，该方法还为基于引导干涉测量或混合配置的更紧凑设置提供了显着优势。此外，为了为各种干涉测量方案及其可以测量的效果的分析提供坚实的基础，开发了一种相对形式描述原子在弯曲时空中相对论的一般形式。它可以处理自由下落的原子，但也包括外力和引导势的影响，可以应用于非常广泛的情况。作为量子时钟干涉测量法的重要组成部分，还研究了原子在内部态叠加中的合适衍射机理。最后，详细讨论了所提出的双微分测量方案与其他实验方法以及自由落体性（UFF）通用性测试之间的关系。建立了相对论性描述弯曲时空中原子干涉的一般形式主义。它可以处理自由下落的原子，但也包括外力和引导势的影响，可以应用于非常广泛的情况。作为量子时钟干涉测量法的重要组成部分，还研究了原子在内部态叠加中的合适衍射机理。最后，详细讨论了所提出的双微分测量方案与其他实验方法以及自由落体性（UFF）通用性测试之间的关系。建立了相对论性描述弯曲时空中原子干涉的一般形式主义。它可以处理自由下落的原子，但也包括外力和引导势的影响，可以应用于非常广泛的情况。作为量子时钟干涉测量法的重要组成部分，还研究了原子在内部态叠加中的合适衍射机理。最后，详细讨论了所提出的双微分测量方案与其他实验方法以及自由落体（UFF）通用性测试之间的关系。并可以应用于非常广泛的情况。作为量子时钟干涉测量法的重要组成部分，还研究了原子在内部态叠加中的合适衍射机理。最后，详细讨论了所提出的双微分测量方案与其他实验方法以及自由落体（UFF）通用性测试之间的关系。并可以应用于非常广泛的情况。作为量子时钟干涉测量法的重要组成部分，还研究了原子在内部态叠加中的合适衍射机理。最后，详细讨论了所提出的双微分测量方案与其他实验方法以及自由落体性（UFF）通用性测试之间的关系。