Non-Isometric Quantum Error Correction in Gravity
In the holographic approach to quantum gravity, quantum information theory plays a fundamental role in understanding how semiclassical gravity emerges from the microscopic description. The map (sometimes called the dictionary) between these two descriptions has the structure of a quantum error correcting code. In the context of an evaporating black hole, this code can be arbitrarily far from an isometry. Such codes are novel from a quantum information standpoint, and their properties are not yet well understood. I will describe a simple toy model of an evaporating black hole which allows for an explicit construction of the dictionary using the Euclidean gravity path integral. I will also describe the sense in which this dictionary is a non-isometric code, explain its basic properties, and comment on implications for semiclassical physics in the black hole interior.