Quantum Gravity in the Lab. II. Teleportation by Size and Traversable Wormholes

In Brown et al. [PRX Quantum, 4, 010321 (2023)], we discuss how holographic quantum gravity may be simulated using quantum devices and we give a specific proposal—teleportation by size and the phenomenon of size winding. Here, we elaborate on what it means to do quantum gravity in the lab and how size winding connects to bulk gravitational physics and traversable wormholes. Perfect size winding is a remarkable fine-grained property of the size wave function of an operator; we show from a bulk calculation that this property must hold for quantum systems with a nearly Ad⁢S₂ bulk. We then examine in detail teleportation by size in three systems—the Sachdev-Ye-Kitaev model, random matrices, and spin chains—and discuss prospects for realizing these phenomena in near-term quantum devices.