Does the survival and sudden death of quadripartite steering in curved spacetime truly depend on multi-directionality?

TL;DR

This study explores how Gaussian quadripartite quantum steering varies with direction in curved spacetime near a black hole, revealing asymmetric behaviors and sudden death phenomena influenced by Hawking radiation.

Contribution

It provides a systematic analysis of the directional dependence and redistribution of quantum steering in black hole backgrounds, highlighting new asymmetric effects and behaviors.

Findings

Steering from non-gravitational to gravitational observers undergoes sudden death at maximal asymmetry.

Steering in the opposite direction decays monotonically and vanishes only in the extreme black hole limit.

Steering from hybrid gravitational-non-gravitational partitions persists at a finite value.

Abstract

We systematically investigate the directional dependence of Gaussian quadripartite quantum steering and its redistribution among different modes in the background of a Schwarzschild black hole. For physically accessible sectors, we identify three distinct behaviors: (i) steering from non-gravitational to gravitational observers undergoes sudden death at maximal asymmetry with the Hawking temperature, marking the crossover from two-way to one-way steerability; (ii) steering in the opposite direction decays monotonically and vanishes only in the extreme black hole limit, highlighting its directional sensitivity to spacetime curvature; (iii) steering from hybrid gravitational-non-gravitational partitions to non-gravitational mode persists at a finite asymptotic value set by the initial squeezing parameter. Moreover, all inaccessible steerings generated by the Hawking effect exhibit an intrinsic asymmetry, with their specific behavior being strongly dependent on the steering direction.