Page Time as a Transition of Information Channels: High-fidelity Information Retrieval for Radiating Black Holes

TL;DR

This paper proposes a new postselection model for black hole information retrieval that allows decoding of interior information from Hawking radiation after the Page time, supported by quantum circuit experiments.

Contribution

It introduces a novel postselection approach that relaxes previous constraints on information recovery in black holes, aligning with the island formula and enabling experimental testing.

Findings

Model produces entropy consistent with the island formula

Interior information can be decoded from Hawking radiation after Page time

Quantum circuits successfully implement decoding strategies on IBM quantum processors

Abstract

The effective field theory description of a radiating black hole introduces redundant degrees of freedom that necessitate annihilation of those modes at late stages to conserve entropy. The prevailing view is that such effective process can result in information loss unless the redundant states are annihilated in maximally entangled pairs, resembling quantum teleportation. In this Letter, we demonstrate that this view can be relaxed in a new postselection model. We investigate information recoverability in a radiating black hole through the non-unitary dynamics that projects the randomly-selected modes from a scrambling unitary. We show that the model has the merit of producing the von Neumann entropy of black holes consistent with the island formula calculation and that information in the black hole interior can be decoded from the Hawking radiation without loss after the Page time. Moreover, in this model the Page time gains a new interpretation as the transition point between two channels of information transmission when sufficient amounts of effective modes are annihilated inside the horizon. We present two decoding strategies along with their quantum circuit realizations. The experimental verification of the strategies employs 7-qubit IBM quantum processors, demonstrating the viability of these strategies and the potential for quantum processors to probe the black hole interior.