Nagoya University
Theoretical Elementary Particle Physics Laboratory

Date&Time Tue Jul 02 2019 (17:00 - 18:00)
Shinji Hirano
Affiliation University of the Witwatersrand, South Africa
Title Information transfer and black hole evaporation via traversable BTZ wormholes
Abstract We study traversable wormholes by considering the duality between BTZ black holes and two-dimensional conformal field theory on the thermofield double state. The BTZ black holes can be rendered traversable by a negative energy shock wave. Following Gao, Jafferis and Wall, it is shown that the negative energy shock wave is dual to the infinite boost limit of a specific double trace deformation which couples the left and right CFTs. We spell out the mechanism of information transfer through traversable BTZ wormholes, treating the backreaction of the message as a positive energy shockwave. The corresponding spacetime is that of colliding spherical shells in the BTZ black hole, which we explicitly construct. This construction allows us to obtain a bound on the amount of information that can be sent through the wormhole, which is consistent with previous work in the context of nearly AdS2 gravity. In addition, our example provides a basic mechanism, the interaction between the positive and negative energy shockwave, through which the black hole entropy on one side of the Kruskal diagram is reduced. We argue that this process can be viewed as a toy model for black hole evaporation. In particular, we find that the time evolution of the information bound follows a curve reminiscent of the Page curve. Finally, we examine the claim that traversable wormholes are fast decoders. We find evidence for this idea by computing the scrambling time in the shockwave background and find it is delayed by the presence of the negative energy shock wave.