Quantum States Prepared by Wormholes: Long-Wavelength Deviations from Bunch-Davies

Abstract

Wineglass wormholes mediate the nucleation of baby universes out of an asymptotically Anti-de Sitter or flat spacetime. Upon materialization, the new universe naturally undergoes an inflationary phase. Here we study the quantum state of tensor and probe scalar field fluctuations that these wormhole geometries prepare, finding that they reproduce the Bunch-Davies vacuum for short-wavelength modes but lead to deviations from Bunch-Davies on large scales. These deviations, which depend on the charge of the wormhole, cause a small shift as well as oscillations in the angular power spectrum generated by an ensuing inflationary phase, and thus provide a distinctive cosmological observable. The wormholes are supported by either axionic or magnetic charges. In the limit of vanishing charge, they undergo a topological transition after which they contain no-boundary instantons. We find that the small-charge limit suppresses deviations from the Bunch-Davies state for both scalar and tensor fluctuations, indicating that the topological transition is smooth.