Full Characterization of the Quantum Effects of Light after Transmission through the Atmosphere

拟议的项目延长的主要目的是“充分描述光在大气层中传输后的量子效应”，并基于我们的第一个提议。因此，我们将继续开发有效的技术来表征大气条件下光的量子态。18个月延长期的研究计划分为大气湍流对多体非经典和多体纠缠的影响两个主要部分。首先，我们希望进一步发展我们的非经典辐射特性的表征技术。在此背景下，我们将把多模非经典矩方法应用于大气湍流损失的情况。此外，我们计划研究光的多体非经典准概率，它包含了量子态的全部信息。这些方法可能需要重新制定现有的测量策略，以根据大气条件进行优化。其次，我们将推广我们对大气信道中辐射场纠缠的研究。预期的第一步是将我们之前对湍流损耗介质中的纠缠的处理推广到多方情形。为此，我们将采用我们的多体纠缠见证的构造方法来推断通过涨落损耗通道传输后的多体量子关联。这第二个资助期的结果将补充我们对湍流大气中量子效应的理论分析，并将导致对量子光学自由空间链路中波动损耗的影响的更深入的理解。特别是，我们计划确定哪些类型的量子效应对大气扰动最稳健。我们对大气量子光学的研究将为设计新的自由空间量子通信方法提供基础。这包括从发送方的正确数据编码、通过持久的量子效应进行的安全数据传输到接收方的最佳检测技术等方面。我们的目标是揭示大气条件，这甚至可能成为量子通信的资源。

The main purpose of the proposed project prolongation is the ''Full Characterization of the Quantum Effects of Light after Transmission through the Atmosphere'' and is based on our first proposal. Therefore, we will continue developing efficient techniques for characterizing the quantum state of light under atmospheric conditions. The research plan of the 18 months of prolongation period is structured into the main parts of atmospheric turbulence effects on multipartite nonclassicality and multipartite entanglement.First, we want to further develop our characterization techniques for nonclassical radiation properties after passing through a turbulent medium. In this context, we will adapt the method of multi-mode nonclassical moments to the case of atmospheric turbulent loss. Furthermore, we plan to investigate multipartite nonclassicality quasiprobabilities of light, which contain the full information on the quantum state. These methods may require to reformulate existing measurement strategies, to optimize them for atmospheric conditions. Second, we will generalize our studies of entanglement of radiation fields in atmospheric channels. The anticipated initial step is a generalization of our previous treatment of entanglement in turbulent loss media to multipartite scenarios. For that purpose we will adapt our construction methods of multipartite entanglement witnesses to infer multipartite quantum correlations of states after propagation through fluctuating-loss channels. The results of this second funding period will complement our theoretical analysis of quantum effects in the turbulent atmosphere and it will result in a deeper understanding of the impact of fluctuating losses in quantum optical free-space links. In particular, we plan to identify those types of quantum effects which are most robust against atmospheric disturbances. Our investigations in atmospheric quantum optics will yield the foundations for designing novel methods of free-space quantum communication. This includes aspects ranging from proper data encoding by the sender, secure data transfer via persisting quantum effects, towards optimal detection techniques at the receiver site. We aim at uncovering atmospheric conditions, which may even serve as a resource for quantum communication.