[Cai, Yi-Fu] Arizona State Univ, Dept Phys, Tempe, AZ 85287 USA
; [Cai, Yi-Fu
; Brandenberger, Robert
; Zhang, Xinmin] Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
; [Brandenberger, Robert] McGill Univ, Dept Phys, Montreal, PQ H3A 2T8, Canada
; [Zhang, Xinmin] Chinese Acad Sci, TPCSF, Beijing 100049, Peoples R China
Massless scalar fields originating in a quantum vacuum state acquire a scale-invariant spectrum of fluctuations in a matter-dominated contracting universe. We show that these isocurvature fluctuations transfer to a scale-invariant spectrum of curvature fluctuations during a non-singular bounce phase. This provides a mechanism for enhancing the primordial adiabatic fluctuations and suppressing the ratio of tensor to scalar perturbations. Moreover, this mechanism leads to new sources of non-Gaussianity of curvature perturbations.