Quantum encrypted communication essentially uses quantum keys for security, and its nature is still based on traditional communication, just with a change in the encryption method.
For example, A sends B a string of quantum characteristic codes, with A recording the deflection angle of each quantum particle at the time of emission, and B recording the deflection angle of each particle upon receipt. According to the quantum entanglement effect, the records at both ends should be consistent.
If a third party discovers this signal and attempts to eavesdrop, the quantum state will change due to the observer effect, and the results obtained by B will be incorrect.
A then openly sends the recorded quantum characteristic code deflection results to B, who compares them; if there are errors, it proves there was eavesdropping, and A would reissue a new characteristic code until both sides are completely consistent.
