arXiv:2602.00991 · The European Physical Journal C
Tripartite quantum steering in Schwarzschild spacetime
Guang-Wei Mi, Xiaofen Huang, Tinggui Zhang
Abstract
We investigate the effects of Hawking radiation on quantum steering and steering asymmetry in a tripartite system embedded in Schwarzschild spacetime. All tripartite steering types were classified,comprising three "1 to 2" and three "2 to 1" steering cases. Through a systematic analysis of all physically relevant scenarios (including accessible and inaccessible modes), we classify three canonical scenarios with one, two and three physically accessible modes. In the scenario of three physically accessible modes, Hawking radiation disrupts quantum steering, with the maximum steering asymmetry during the two-way steering to one-way steering transition precisely demarcating the phase boundary between these regimes. For two physically accessible modes, Hawking radiation exhibits dual behavior: enhancing the steering from Alice and Bob to anti-Charlie under certain parameters while suppressing it under others, while net strengthening other steering types. When considering one physically accessible mode, the Hawking effect of the black hole significantly enhances quantum steering. These findings provide new insights into quantum correlations in curved spacetime and establish observable signatures of Hawking effects in quantum steering phenomena.
AI Summary
The paper studies how Hawking radiation affects directional steering across the three bipartitions of a generalized three-qubit GHZ state, $\alpha|000\rangle+\sqrt{1-\alpha^2}|111\rangle$, in Schwarzschild spacetime. Alice remains asymptotically far away, while Bob and Charlie are placed near the horizon. A standard fermionic Bogoliubov transformation introduces exterior particle and interior antiparticle modes, with Hawking temperature $T=1/(8\pi M)$. Tracing out different modes produces three-qubit X states containing three, two, or one exterior modes. Steering is detected through entanglement of auxiliary states obtained by adding local maximally mixed noise: the sufficient criteria use mixing parameters $1/\sqrt{3}$ for $1\rightarrow2$ steering and $1/3$ for $2\rightarrow1$ steering. Explicit inequalities yield normalized witness-based steering quantities for all six directions. Their temperature dependence is examined analytically and through plots at $\omega=1$ and $\alpha\in\{1/4,1/2,1/\sqrt{2}\}$. For the all-exterior subsystem, the reported steering quantities decrease with temperature; some $2\rightarrow1$ quantities vanish at finite temperature, while reciprocal quantities persist. Maximum asymmetry is reported at transitions classified as two-way to one-way steering. Subsystems containing interior modes exhibit increasing steering quantities, with nonmonotonic behavior in one direction and parameter-dependent onset thresholds. The treatment is restricted to this GHZ family and idealized field-mode description. Interior modes are explicitly acknowledged to be inaccessible to exterior observers. No dedicated limitations discussion is provided; importantly, the construction supplies sufficient steering witnesses, rather than necessary-and-sufficient tests establishing unsteerability when a witness vanishes.
Central claim may not hold: The paper treats failure of sufficient steering witnesses as proof of unsteerability, so its asserted one-way regimes and exact two-way–to–one-way boundaries are not established. The formulas for AB→C and CA→B steering give different results for a state invariant under exchanging B and C, invalidating the claimed distinction between their disappearance behaviors. The five-mode state prints an excited-state contribution |11111⟩ where the stated mode transformation requires |11010⟩, although the subsequent reduced states correspond to the corrected term.
Written by gpt-6.1-sol from the paper's full text. Automated: it can be wrong.
- Journal reference
- Eur. Phys. J. C (2026) 86:75
- DOI
- 10.1140/epjc/s10052-025-15241-3
- Comments
- 15pages, 3 figures