Influence of random media on orbital angular momentum quantum states of optical vortex beams

Photonic orbital angular momentum (OAM) carrying orthogonal modes exhibits fascinating nature for information encoding. Here we focus on the propagation of OAM states in random media to investigate the turbulence-induced OAM degradation. We utilize the quadratic approximation of the phase structure function to derive a global continuous expression of OAM probability at the single-photon level. The expression provides a general insight into the energy transition between signal and crosstalk modes in random media. Especially for each crosstalk mode, our expression is accurate in predicting the second-order energy transition. The effectiveness of our model is validated via experimental data and simulations in various random media. We also reveal the universality of entangled optical vortex beams and obtain an expression of concurrence. It is demonstrated that utilizing high-order optical vortex beams can effectively improve the antijamming ability and enhance the propagation distance of entanglement. Our results provide a universal framework for OAM propagation through different random media.