Generalized Free Fields in de Sitter from 1D CFT

We show that a pair of identical large $N$ 1D CFTs, like the low-energy limit of the SYK model or a line-defect inside a higher dimensional CFT, contains a natural sub-algebra of operators that comprise a generalized free field algebra living on a time-like geodesic in d+1-dimensional de Sitter spacetime. The construction uses large $N$ factorization, 1D conformal symmetry, and the split representation of de Sitter Green functions. We show that for 3D de Sitter spacetime, the holographic map extends into the bulk and reduces to the standard HKLL prescription adjusted to de Sitter spacetime. We describe how our construction is automatically implemented in a covariant version of Schwarzian quantum mechanics and comment on the relevance of our results to the de Sitter/DSSYK correspondence.