Nearly scale-invariant curvature modes from entropy perturbations during the graceful exit phase

In this Letter, we describe how a spectrum of entropic perturbations generated during period slow contraction can source nearly scale-invariant curvature on length scales larger than the Hubble radius transition from to classical non-singular bounce (the `graceful exit' phase). The sourcing occurs naturally through higher-order scalar field kinetic terms common (non-singular) mechanisms. We present concrete example in which, by end graceful exit phase, initial fluctuations have become negligible and with an amplitude consistent observations.