  In [1] we discussed how quantum gravity may be simulated using quantum
devices and gave 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 wavefunction of an operator; we show from a bulk
calculation that this property must hold for quantum systems with a
nearly-AdS_2 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.
