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Figure 1: Concept diagram of (a) using a single-end AO module for the bi-directional coaxis OAM mode propagation through atmospheric turbulence and (b) simultaneous pre- and post-AO compensation for a turbulence-induced, OAM-encoded, and bi-directional quantum communication link. TX-1/2: transmitter for the forward/backward quantum channel; RX-1/2: receiver for the forward/backward quantum channel; SPD: single photon detector.