Entangled Scalar and Tensor Fluctuations during Inflation

TL;DR

This paper investigates how initial entanglement between scalar and tensor fluctuations during inflation alters the cosmic microwave background's angular correlations, providing exact solutions and potential observational signatures.

Contribution

It introduces a framework for analyzing entangled inflationary states and derives exact propagators and power spectra for such states, extending beyond the standard Bunch-Davies vacuum.

Findings

Exact solutions for entangled initial states' propagators.

Modified angular power spectra due to entanglement.

Potential observational signatures in CMB correlations.

Abstract

We show how the choice of an inflationary state that entangles scalar and tensor fluctuations affects the angular two-point correlation functions of the $T$, $E$, and $B$ modes of the cosmic microwave background. The propagators for a state starting with some general quadratic entanglement are solved exactly, leading to predictions for the primordial scalar-scalar, tensor-tensor, and scalar-tensor power spectra. These power spectra are expressed in terms of general functions that describe the entangling structure of the initial state relative to the standard Bunch-Davies vacuum. We illustrate how such a state would modify the angular correlations in the CMB with a simple example where the initial state is a small perturbation away from the Bunch-Davies state. Because the state breaks some of the rotational symmetries, the angular power spectra no longer need be strictly diagonal.