Fate of the False Vacuum: Finite Temperature, Entropy, and Topological Phase in Quantum Simulations of the Early Universe

Despite being at the heart of the theory of the Big Bang and cosmic inflation, the quantum-field-theory prediction of false vacuum tunneling has not been tested. To address the exponential complexity of the problem, a table-top quantum simulator in the form of an engineered Bose-Einstein condensate (BEC) has been proposed to give dynamical solutions of the quantum-field equations. In this paper, we give a numerical feasibility study of the BEC quantum simulator under realistic conditions and temperatures, with an approximate truncated Wigner phase-space method. We report the observation of false vacuum tunneling in these simulations, and the formation of multiple bubble universes with distinct topological properties. The tunneling gives a transition of the relative phase of coupled Bose fields from a metastable to a stable vacuum. We include finite-temperature effects that would be found in a laboratory experiment and also analyze the cutoff dependence of modulational instabilities in Floquet space. Our numerical phase-space model does not use thin-wall approximations, which are inapplicable to cosmologically interesting models. It is expected to give the correct quantum treatment, including superpositions and entanglement during dynamics. By analyzing a nonlocal observable called the topological phase entropy (TPE), our simulations provide information about phase structure in the true vacuum. We observe a cooperative effect in which true vacua bubbles representing distinct universes each have one or the other of two distinct topologies. The TPE initially increases with time, reaching a peak as multiple universes are formed, and then decreases with time to the phase-ordered vacuum state. This gives a model for the formation of universes with one of two distinct phases, which is a possible solution to the problem of particle-antiparticle asymmetry.

Automated summary

This paper discusses the feasibility of studying false vacuum tunneling using a BEC quantum simulator, observing false vacuum tunneling and the formation of multiple bubble universes with distinct topological properties. By analyzing the topological phase entropy, a model for the formation of universes with two distinct phases in the true vacuum is proposed.