In search of an observational quantum signature of the primordial perturbations in slow-roll and ultra slow-roll inflation

Understand

In the standard inflationary paradigm, cosmological density perturbations are generated as quantum fluctuations in the early Universe, but then undergo a quantum-to-classical transition.

• A key role in this transition is played by squeezing of the quantum state, which is a result of the strong suppression of the decaying mode component of the perturbations.
• Motivated by ever improving measurements of the cosmological perturbations, we ask whether there are scenarios where this decaying mode is nevertheless still observable in the late Universe, ideally leading to a ``smoking gun'' signature of the quantum nature of the perturbations.
• We address this question by evolving the quantum state of the perturbations from inflation into the post-inflationary Universe.