We propose alternative UV completion of pure JT gravity as well as CFT coupled to JT gravity, via a class of deformed 2D CFT. In AdS/CFT with a prescribed classical limit, pure JT gravity in one-sided AdS₂ black hole is argued to be described by certain holographic deformed CFT on a strip. Equivalently, these deformed CFTs can be recast as CFTs on one-sided AdS₂ black hole with emergent conformal boundary condition on a stretched horizon-providing a proper UV frame of JT gravity. On the other hand, JT gravity coupled to CFT with fixed central charge of O (1), is also described by deformed CFT on strip satisfying conformal boundary condition, with a different classical limit. The resulting CFT Hilbert spaces in both of the above classical limits yield the black hole entropy as thermal entropy and the high-energy density of states match that of JT gravity with a precise energy scale correspondence. Moreover, the Hilbert space defined for a two-sided black hole factorizes into two one-sided sectors in both limits. Notably in the second limit, degenerate zero modes of the deformed Hamiltonian-characterized by conformal primaries localized at the horizon-appear as a residual effect of the stretched horizon boundary condition. Exploiting the second limit, we compute entanglement entropy in one-dimensional quantum systems dual to a conformally glued black hole-Poincaré geometry in JT gravity, reproducing a `Page curve' via the quantum extremal surface prescription, with `Page time' set by the stretched horizon cutoff.
Das et al. (Wed,) studied this question.