Detection of quantum entanglement across the event horizon

TL;DR

This paper explores the theoretical possibility of distinguishing entangled quantum states when one particle crosses a black hole's event horizon, revealing fundamental limits on quantum state localizability.

Contribution

It demonstrates that, despite intuitive expectations, quantum state discrimination can distinguish between states with one particle inside a black hole and those outside.

Findings

Quantum state discrimination can differentiate entangled states across an event horizon.

Fundamental limits on localizability enable distinguishability of such states.

Analysis identifies configurations maximizing discrimination success.

Abstract

We investigate the problem of distinguishing between separable and entangled states of two quantum wave packets, one of which falls into a black hole. Intuitively, one might expect the two scenarios to be indistinguishable, since the information carried by one wave packet is hidden beyond the event horizon. We show, however, that fundamental limitations on the localizability of quantum states render the two scenarios, in principle, distinguishable. Employing tools from quantum state discrimination theory, we analyze a concrete realization and discuss the configurations that maximize the probability of successfully distinguishing between the two cases.