Quantum Fisher Information in Curved Spacetime: Dirac Particles in Noisy Channels around a Schwarzschild Black Hole

Quantum information processing promises significant advantages over classical methods but remains vulnerable to decoherence induced by environmental interactions and spacetime effects. This work investigates the behavior of Quantum Fisher Information (QFI) as a diagnostic tool for entanglement and parameter estimation in a three-qubit entangled Dirac system subjected to dissipative noisy channels in the curved spacetime of a Schwarzschild black hole. In particular, we examine the influence of the squeezed generalized amplitude damping (SGAD) channel, along with its subchannels– generalized amplitude damping (GAD) and amplitude damping (AD)– on the QFI with respect to entanglement weight (\(\theta\)) and phase (\(\phi\)) parameters. Our results show that under strong squeezing (\(r = 1\)), the QFI with respect to \(\theta\) becomes completely resistant to variations in the Hawking temperature (\(T_H\)), while still exhibiting degradation with increasing channel temperature (\(T_C\)). The QFI decay is significantly slower at \(r = 1\) compared to \(r = 0\), suggesting that squeezing can function as an error mitigation strategy. For QFI with respect to \(\phi\), a transient spike is observed at \(T_C = 2\), potentially due to thermal resonance or non-monotonic decoherence, and this behavior is unaffected by \(T_H\). Similar patterns are noted in the GAD and AD channels, where \(T_C\) consistently dominates as the principal source of decoherence. Overall, the results highlight the intricate interplay between environmental noise, relativistic effects, and quantum error resilience in curved spacetime.