Electromagnetic Modeling and Capacity Analysis of Rydberg Atom-Based MIMO System

Rydberg atom-based antennas exploit the quantum properties of highly excited Rydberg atoms, providing unique advantages over classical antennas, such as high sensitivity, broad frequency range, and low intrinsic noise. Despite the increasing interests in their applications in antenna and communication engineering, some key properties, involving the lack of polarization multiplexing and isotropic reception without mutual coupling, remain unexplored in the analysis of Rydberg atom-based multiple-input–multiple-output (MIMO) communications. Generally, the design considerations for any antenna, even for atomic ones, can be extracted to factors, such as radiation pattern, efficiency, and polarization, allowing them to be seamlessly integrated into existing system models. In this letter, we extract the antenna properties from relevant quantum characteristics, enabling electromagnetic modeling and capacity analysis of Rydberg MIMO systems in both far-field and near-field scenarios. Focusing on spatial multiplexing performance under the same signal-to-noise level, our results indicate that Rydberg atom-based antenna arrays offer certain advantages over classical dipole-type arrays in single-polarization MIMO communications.