Escaping the Interiors of Pure Boundary-State Black Holes

TL;DR

<3-5 sentence high-level summary> The work studies a class of pure black hole microstates dual to BCFT boundary conditions involving End-of-the-World branes and shows that a state-dependent double-trace deformation in the boundary theory can inject negative energy, making the interior escapable and effectively turning the interior behind the horizon into a traversable region. Escapability is demonstrated through two probes: a negative horizon stress tensor consistent with traversable wormholes and an enhanced early/late-time commutator signaling information escape, with a careful treatment of the state-dependence required for ANEC violation. The analysis connects boundary-state microphysics to bulk brane dynamics, outlines how interior operators can be reconstructed in the deformed geometry, and discusses limitations such as late-time escapability and the necessity of state-dependent reconstructions. The results illuminate how specific BCFT/ETW-brane configurations can influence interior access and highlight the role of state dependence in interior reconstruction within holography.

Abstract

We consider a class of pure black hole microstates and demonstrate that they can be made escapable by turning on certain double trace deformations in the CFT. These microstates are dual to BCFT states prepared via a Euclidean path integral starting from a boundary in Euclidean time. These states are dual to black holes in the bulk with an End-of-the-World brane; a codimension one timelike boundary of the spacetime behind the horizon. We show that by tuning the sign of the coupling of the double trace operator to the boundary conditions on the brane the deformation injects negative energy into the black hole causing a time advance for signals behind the horizon. We demonstrate how the property of escapability in the considered microstates follows immediately from the traversability of deformed wormholes. We briefly comment on reconstruction of the black hole interior and state dependence.

Figures (12)

• Figure 1: The coordinate transformation \ref{['coordtransf']} maps the UHP to the strip. The state $| B \rangle$ should be thought as prepared on the boundaries of the strip.
• Figure 2: The bulk (green) is bounded by the asymptotic boundary at $z = 0$, and the brane (red) shooting off at an angle $\theta$ in the $z-\tau$ plane, hits the boundary at $\tau=0$. Transverse directions are suppressed.
• Figure 3: Allowed positive tension brane configurations in the Euclidean/Lorenztian BTZ geometry. Left: The trajectory of the End-of-The-World (ETW) brane (red) in the Euclidean geometry. Middle: Euclidean preparation of the Lorentzian ETW brane BTZ state. Right: Full Lorenztian solution of ETW brane BTZ black hole. The shaded region is the excluded region of the original eternal BTZ black hole solution.
• Figure 4: Left: Zero tension ETW brane. The solution can be thought of as a $Z_2$ orbifold of the original eternal black hole solution. Right: Negative tension ETW brane. From the right exterior this solution looks like a brane which emerges from the white hole and falls into the black hole.
• Figure 5: The point-split correlation function in the B-State black hole can be expressed as a sum/difference of a correlation functions in the BTZ background. The blue corresponds to a retarded Green's function, while the orange corresponds to a Feynman's Green's function. The first contribution on the right side does not contribute to the integral of the stress tensor on the horizon. The second term is precisely that of the traversable wormhole.