Constraining Quantum Initial Conditions before Inflation

Understand

We theoretically and observationally investigate different choices of initial conditions for the primordial mode function that are imposed during an epoch preceding inflation.

• By deriving predictions for the observables resulting from several alternate quantum vacuum prescriptions we show some choices of vacua are theoretically observationally distinguishable from others.
• Comparing these predictions to the Planck 2018 observations via a Bayesian analysis shows no significant evidence to favour any of the quantum vacuum prescriptions over the others.
• In addition we consider frozen initial conditions, representing a white-noise initial state at the big-bang singularity.