Yame Mwanzang Philemon

arXiv2025

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 ($θ$) and phase ($ϕ$) parameters. Our results show that under strong squeezing ($r = 1$), the QFI with respect to $θ$ 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 $ϕ$, 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.

quant-ph↗

arXiv2024

Wireless Multihop Quantum Teleportation Utilizing a 4-Qubit Cluster State

This paper proposes a quantum routing protocol using multihop teleportation for wireless mesh backbone networks. After analyzing the quantum multihop protocol, a four-qubit cluster state is selected as the quantum channel for the protocol. The quantum channel between intermediate nodes is established through entanglement swapping, utilizing the four-qubit cluster state. Additionally, both classical and quantum routes are created in a distributed manner. We demonstrate that quantum information can be teleported hop-by-hop from the source node to the destination node. Successful quantum teleportation occurs when the sender performs Bell state measurements (BSM), while the receiver introduces auxiliary particles, applies a positive operator-valued measure (POVM), and uses a corresponding unitary transformation to recover the transmitted state. We analyze the success probability of quantum state transfer and find that the optimal success probability is achieved when $τ_{2|1} = \frac{1}{\sqrt{2}}$. Our numerical results show the susceptibility of $P_{\text{suc}}$ to the number of hops $N$. These findings indicate that multihop teleportation using distributed wireless quantum networks with a four-qubit cluster state is feasible.

quant-ph↗