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The European Physical Journal C

Nonlocal correlations of fermionic entanglement in the spacetime of Einstein–Gauss–Bonnet black hole

Yifei Xu, Yanjun Chen, Qi Xiao, Xiaolong Gong

Published Aug 1, 2026• 0 citations
Publisher

Abstract

Abstract The investigation of nonclassical correlations in curved spacetimes offers key insights into the intersection of quantum information theory and gravitational physics. This paper studies two nonlocal correlation measures, non local advantage of quantum coherence (NAQC) and Bell nonlocality (BN) in a d -dimensional spherically symmetric Einstein–Gauss–Bonnet (EGB) black hole spacetime. We consider two observers (Alice and Rob) initially sharing a maximally entangled Bell state: Alice freely falls into the black hole (inertial Kruskal frame), while Rob accelerates outside the horizon (non-inertial Schwarzschild-like frame). The Unruh–Hawking effect modifies Rob’s field modes, requiring Bogoliubov transformations to relate the two frames. We derive the mixed bipartite density matrix for fermionic fields and analytical expressions for NAQC and BN, which depend on Hawking temperature (itself governed by $$\alpha $$ α , d , and $$r_h$$ r h ). Our results show both correlations degrade monotonically with increasing Hawking temperature, confirm the NAQC-BN hierarchical relationship persists in EGB spacetime, and highlight higher-curvature corrections’ impact on quantum resources.

DOI
10.1140/epjc/s10052-026-16161-6

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The investigation of nonclassical correlations in curved spacetimes offers key insights into the intersection of quantum information theory and gravitational physics. This paper studies two nonlocal correlation measures, non local advantage of quantum coherence (NAQC) and Bell nonlocality (BN) in a ddd-dimensional spherically symmetric Einstein-Gauss-Bonnet (EGB) black hole spacetime. We consider two observers (Alice and Rob) initially sharing a maximally entangled Bell state: Alice freely falls into the black hole (inertial Kruskal frame), while Rob accelerates outside the horizon (non-inertial Schwarzschild-like frame). The Unruh-Hawking effect modifies Rob's field modes, requiring Bogoliubov transformations to relate the two frames. We derive the mixed bipartite density matrix for fermionic fields and analytical expressions for NAQC and BN, which depend on Hawking temperature (itself governed by ααα, ddd, and rhr_hrh​). Our results show both correlations degrade monotonically with increasing Hawking temperature, confirm the NAQC-BN hierarchical relationship persists in EGB spacetime, and highlighting the impact of high curvature corrections on quantum resources.
Abstract We investigate the hierarchy of nonlocal correlations for Dirac fields in the Schwarzschild de Sitter (SdS) spacetime. We find that the hierarchical relationship between the nonlocal advantage of quantum coherence (NAQC) and Bell nonlocality remains in the multi-event horizon curved spacetime. It is demonstrated that the NAQC and Bell nonlocality provide a more rigorous characterization of physically inaccessible quantum properties than coherence, as classical information cannot be transmitted across the thermally opaque membrane. Furthermore, when considering an effective equilibrium temperature, an enhancement in quantum nonlocality with increasing temperature is observed, which challenges the conventional understanding that the Hawking effect solely diminishes quantum nonlocality. This study contributes to integrating quantum resource theory within the context of multi-event horizon black holes.
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Abstract We investigate how the Hawking effect reshapes distinct quantum resources of Dirac fields in Schwarzschild spacetime beyond the single-mode approximation. By quantifying quantum entanglement and coherence using the negativity, the l 1 -norm of coherence and the relative entropy of coherence, we observe a significant asymmetry in their response to gravitational effects. While the Hawking effect monotonically degrades entanglement and drives it toward a finite residual value, quantum coherence is instead monotonically amplified with increasing Hawking temperature, revealing the black hole as an effective decohering environment for nonlocal correlations but a coherence-enhancing mechanism for local superposition. Notably, we further find that under the influence of the Hawking effect, the maximally entangled state does not necessarily correspond to the largest initial negativity. In fact, its value may even be smaller than that of certain non-maximally entangled states. Our results demonstrate that gravity acts in a highly nonuniform manner on different facets of quantumness and highlight the necessity of resource-adapted state engineering for relativistic quantum information processing near the event horizon of the black hole.
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