Holographic multiple-input multiple-output (HMIMO) utilizes a compact antenna array to form a nearly continuous aperture, thereby enhancing higher capacity and more flexible configurations compared with conventional MIMO systems, making it attractive in current scientific research. Key questions naturally arise regarding the potential of HMIMO to surpass Shannon's theoretical limits and how far its capabilities can be extended. However, the traditional Shannon information theory falls short in addressing these inquiries because it only focuses on the information itself while neglecting the underlying carrier, electromagnetic (EM) waves, and environmental interactions. To fill up the gap between the theoretical analysis and the practical application for HMIMO systems, we introduce electromagnetic information theory (EIT) in this paper. This paper begins by laying the foundation for HMIMO-oriented EIT, encompassing EM wave equations and communication regions. In the context of HMIMO systems, the resultant physical limitations are presented, involving Chu's limit, Harrington's limit, Hannan's limit, and the evaluation of coupling effects. Field sampling and HMIMO-assisted oversampling are also discussed to guide the optimal HMIMO design within the EIT framework. To comprehensively depict the EM-compliant propagation process, we present the approximate and exact channel modeling approaches in near-/far-field zones. Furthermore, we discuss both traditional Shannon's information theory, employing the probabilistic method, and Kolmogorov information theory, utilizing the functional analysis, for HMIMO-oriented EIT systems.

翻译：全息多输入多输出技术利用紧凑天线阵列形成近乎连续的孔径，相较于传统MIMO系统具有更高容量和更灵活配置的优势，因而成为当前科学研究的热点。自然会引发关键问题：全息MIMO能否超越香农理论极限？其能力边界又在哪里？然而传统香农信息论难以回答这些问题，因其仅关注信息本身，而忽略了底层载体——电磁波及其与环境的交互作用。为填补全息MIMO系统理论分析与实际应用之间的鸿沟，本文引入电磁信息理论。本文首先构建面向全息MIMO的电磁信息理论基础，涵盖电磁波动方程与通信区域。在HMIMO系统背景下，给出物理限制分析，包括Chu极限、Harrington极限、Hannan极限以及耦合效应评估。在EIT框架下讨论场采样与HMIMO辅助过采样以指导最优系统设计。为全面描述符合电磁规律的传播过程，提出近/远场区域的近似与精确信道建模方法。此外，针对HMIMO导向的EIT系统，分别讨论采用概率方法的传统香农信息论与采用函数分析的柯尔莫哥洛夫信息论。