Recovering Infalling Information via String Spreading

TL;DR

This paper demonstrates that string spreading near black hole horizons can facilitate information transfer from infalling matter to late-time detectors, suggesting a mechanism for information recovery in black hole physics.

Contribution

It extends the concept of string spreading to closed strings and shows it can enable significant information retrieval from black holes, supported by S-matrix evidence and eikonal resummation.

Findings

String spreading induces strong interactions at large time separations.

Late-time detectors can recover a significant fraction of infalling information.

String effects may play a role in resolving the black hole information paradox.

Abstract

We find S-matrix evidence that longitudinal string spreading can induce interactions between early and late time systems in the near-horizon region of a black hole. By generalizing the effect to closed strings and performing an eikonal resummation, we find a tractable regime where these interactions become strong at a Schwarzschild time separation $\Delta t \gg r_s$. We estimate the mutual information in a scenario analogous to Hayden-Preskill, and we find that string spreading is sufficient in itself for a late-time detector to recover a significant fraction of the information encoded in an infaller's state. Interesting open directions include analysis of the interaction of the detector with Unruh radiation (which may introduce noise that somewhat degrades the recovery), and formulating the optimal detector setup including many entangled detectors (which could further increase the information recovery by enhancing sensitivity to kinematic parameters with subleading dependence in the amplitude).