Recovering information in an asymptotically flat spacetime in quantum gravity

TL;DR

This paper proposes a protocol for observers in flat spacetime to detect pure quantum states in the bulk, demonstrating holography of information in asymptotically flat spacetime.

Contribution

It introduces a physical protocol involving unitary operations and energy measurements for bulk state detection in flat spacetime, extending previous holography results.

Findings

Protocol enables detection of bulk pure states near null infinity.

Holography of information is shown to hold in asymptotically flat spacetime.

Analysis is valid for low-energy, massless excitations in 3+1 dimensions.

Abstract

As an extension of arXiv:\{2002.02448, 2008.10740\} we present a physical protocol that a set of observers can use to detect a pure state in the bulk when they are spread across a small cut near $\mathcal{I}^+_-$ in flat spacetime. The protocol involves the modification of a bulk state using simple unitary operators and measurements of the energy of the state. The states that we study are constructed by acting with low energy operators on a vacuum state such that a perturbative analysis is valid. We restrict ourselves to $3+1$ dimensional spacetimes and only consider massless excitations. From this analysis, the principle of holography of information becomes manifest in the case of asymptotically flat spacetime.