Islands and traversable wormholes

Abstract

We study information recovery in black hole evaporation using traversable wormhole protocols in AdS$_2$ Jackiw-Teitelboim gravity with matter fields coupled to an external bath. By introducing a simple non-local interaction between left and right radiation regions, we generate negative-energy shockwaves that render the wormhole traversable. We compute the resulting shifts in Kruskal coordinates, changes in the stress tensor, and backreaction effects on quantum extremal surfaces, finding a consistent decrease of the generalized entropy that aligns with the flat Page curve. Finally, we analyze the impact of negative-energy shocks on boundary two-point functions, providing a microscopic probe of island/radiation duality and discussing possible implications for experimental realizations in analog quantum-mechanical models.

Figures (7)

• Figure 1: Eternal black hole coupled to a bath. Left: Early time configuration where the empty island dominates and gives rise to the linear increase of the entanglement entropy. Right: Configuration where an island shows up at late times. This saddle is responsible of the flatness of the entropy curve.
• Figure 2: The blue/red lines represent the regions of space where we have negative/positive energy density.
• Figure 3: Energy shock waves produced by the non-local deformation in the conformaly flat geometry.
• Figure 4: We compute the change in entanglement entropy associated to the blue diamonds.
• Figure 5: Impact of negative-energy shock waves on the normalized two-sided two-point function $g_2(t)$, as defined in Eq. (\ref{['eq-nomalized2pfunction']}). Shock waves with varying energy, distinguished by color, are introduced at $t_0 = 1.5$, resulting in a discontinuity whose magnitude increases with increasing $|E_s|$. At later times $t \gg t_0$, the perturbed two-point functions converge back to the unperturbed result (dashed line), following the same trajectory regardless of the shock wave energy.