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Abstract

The prediction of CMB B-modes from Inflation typically begins with a study of the paths of photons in an expanding universe in the presence of a classical gravity wave. This gravity wave is assumed to be drawn for a stochastic bath. However, a natural mechanism for the origin of this bath is quantum graviton creation at the end of inflation, which naturally leads a squeezed vacuum state, not the coherent state of a classical wave. In an attempt to bridge this gap, several mechanisms for a quantum to classical transition have been proposed, and will be reviewed. The possibility that no such transition occurs will also be considered. The resulting additional fluctuations in the photon paths will be discussed.