4. Significance and Challenges

4.1 Overcoming the limitations of terrestrial networks

Quantum satellite communications provide global-scale quantum connectivity by minimizing signal loss – unlike terrestrial links, which are affected by absorption in optical fibers (a typical high-performance telecommunications fiber has a loss of approximately 0.2 dB/km). Since quantum states cannot be amplified without perturbation (due to the no-cloning theorem), the efficiency of the link decreases exponentially with distance in the optical fiber, as illustrated in Figure 5 (excerpted and translated from...