Speaker
Description
In this talk, we quantitatively characterise the phase of primordial perturbations from inflation to cosmic microwave background scales. Our goal is to analyse how the phase of those perturbations evolve through the entire expansion history of the universe and to identify theoretical reference values that can be tested against future observations.
To achieve this, we study the quantum squeezing of the Mukhanov–Sasaki variable and its associated phase within a Gaussian framework, with the system evolved through the radiation- and matter-dominated eras. In each epoch, the evolution is initialised using the Deruelle–Mukhanov matching conditions, ensuring consistent tracking of the mode functions across cosmological transitions. We recover the standard result that inflation makes the phase probability distribution sharply peaked, leading to phase coherence as the mode evolves outside the horizon, and we show that this imprint persists beyond inflation.
A central result is the universality of the phase coherence value within slow-roll, single-field inflationary models, even when modes experience different numbers of e-folds, as in grand-unified compared to electroweak-scale inflation. This universality results from the essential role of reheating and the radiation era, which must be modelled consistently.
Overall, this provides an exact theoretical reference for the phase variance, to be tested against future observations of phase coherence in the cosmic microwave background, E-mode polarisation, and large-scale structure.