Why does the channel capacity of a quantum communication system using entangled photons degrade under decoherence?

💡 Explanation

Decoherence causes a loss of quantum entanglement, thereby reducing the number of effectively usable qubits for communication. Because channel capacity depends directly on the number of qubits, its degradation results from diminished entanglement, therefore reducing effective channel capacity, rather than just from increased noise or signal distortion.

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