Two-mode Quantum Entanglement dynamics of underwater quantum communication

Quantum communication provides a powerful tool for communication with information-theoretic security and high private capacity. However, until now, almost all studies on underwater quantum communication have been based on the polarization or orbital angular momentum of the single-photon state. Because quantum entanglement is an important resource in quantum communication, it is an interesting but still open question as to whether quantum entanglement still exists after interaction with water and underwater objects. In this study, we use the air-water-metal three-layer model as an example and investigate the dynamics of the output entangled state when both modes are sent through the water. Our results show that strong entanglement exists even after interaction with shallow water, and underwater quantum communication with two-mode quantum entanglement is thus feasible in typical quantum communication scenarios.