We study an inflation model with a flat scalar potential supported by observations and find that slow-roll inflation can emerge after a quasicyclic phase of the Universe, where it undergoes repeated expansions and contractions for a finite time period. The initial conditions and the positive spatial curvature required for such nontrivial dynamics align with the quantum creation of the Universe. The key ingredients that trigger inflation are dissipative interactions of the inflaton, which are necessary to reheat the Universe after inflation and thus give us an observational handle on preinflationary physics. Our discovery implies that inflation occurs more robustly after the creation.

• Received 17 May 2023
• Accepted 10 April 2024

DOI:https://doi.org/10.1103/PhysRevD.109.L101303