De Sitter holographic complexity from Krylov complexity in DSSYK

Abstract: We utilize the recent connection between the high energy limit of the double-scaled SYK model and two-dimensional de Sitter solutions of sine dilaton gravity to identify the length of a family of geodesics spanned between future and past infinities with Krylov spread complexity. This constitutes an explicit top-down microscopic realization of holographic complexity in a cosmological spacetime. Our identification is different from the existing holographic complexity proposals for de Sitter geometries which are anchored either on horizons as holographic screens or on timelike observers. This leads us to introduce and investigate a new cosmological holographic complexity proposal in any dimension. It is based on extremal timelike volumes anchored at the asymptotic past and future and at large values of the anchoring boundary coordinate grows linearly with growth rate proportional to the product of de Sitter entropy and temperature.