Quantum MIMO Diversity Framework Using Approximate Cloning and Probabilistic Purification

Quantum communication serves as a foundational technology for distributed quantum computing and quantum sensing. This work presents a quantum multiple-input multipleoutput (MIMO) diversity framework based on approximate cloning and probabilistic purification for discrete-variable (DV) quantum channels. In the proposed framework, approximate quantum cloning is employed at the transmitter to distribute quantum information across multiple noisy channels, while a probabilistic purification process at the receiver coherently combines the received states to reconstruct a higher-fidelity output. The communication channels are modeled with both depolarizing noise and crosstalk effects using controlled-SWAP operators. To enhance end-to-end fidelity, a semi-definite programmingbased purification strategy is developed, jointly optimizing the cloning asymmetry and the purification map. Numerical results demonstrate that the proposed cloning-purification approach achieves superior fidelity compared to best-channel selection and other baseline schemes when full channel state information (CSI) is available, and that symmetric configurations remain robust under limited or no CSI conditions.