A relativistic-quantum-information result showing how placing a finite-lifetime (causal-diamond) observer in a quantum superposition of spacetime trajectories reshapes the entanglement of Dirac fields. It derives the Unruh-diamond vacuum for Dirac fields via the conformal Rindler-to-diamond mapping and shows that, while a classical diamond spacetime degrades shared entanglement through an Unruh-like thermal effect tied to the observer's apparent horizon, a superposed diamond spacetime acts as a superposed quantum channel that generates additional entanglement between both correlated and uncorrelated modes, casting spacetime superposition as a quantum-information resource.
This paper (gr-qc, quant-ph; Eur. Phys. J. C 85, 539 (2025)) studies the generation and degradation of quantum entanglement for Dirac fields in a superposed causal diamond spacetime, from the standpo…