Wen-Mei Li, Jianbo Lu, Shu-Min Wu

We study physically accessible and inaccessible N-qubit coherence of the mixed Greenberger-Horne-Zeilinger (GHZ) and W states for bosonic and fermionic fields when any $n$ ($n<N$) qubits hover over the Schwarzschild black hole. We derive a comprehensive analytical expression for the coherence of mixed N-qubit systems, taking into account both accessible and inaccessible components in the curved spacetime background. Notably, as the number of qubits increases in the mixed W state, its coherence becomes more robust against the degrading effects of Hawking radiation, even as entanglement becomes more fragile. Moreover, with increasing Hawking temperature, W-state coherence surpasses that of the GHZ state, while the entanglement of the W state remains consistently weaker than that of the GHZ state. Interestingly, in Schwarzschild spacetime, fermionic fields exhibit stronger multiqubit entanglement, while bosonic fields show greater multiqubit coherence, revealing a fundamental contrast in their behavior under strong gravity. Our study reveals how Schwarzschild spacetime reshapes quantum resource trade-offs across states, statistics, and correlations, guiding relativistic quantum information tasks.