Holographic complexity of axion-de Sitter universes

Abstract: We study the holographic complexity of a pair of asymptotically dS universes in the presence of axion matter, to characterize these observables in more general spacetimes. The system is prepared in a two-copy Hartle-Hawking state by slicing an Euclidean wormhole, which entangles the two universes. We derive the evolution of codimension-1 Complexity=Anything proposals by anchoring the probes to a worldline observer in each of the universes and connecting them through the Euclidean wormhole. We investigate how the axion charge competes with the cosmological constant in the time evolution of complexity. When the complexity proposal equals the volume of an extremal surface, its evolution is determined by the scale factor of the axion-dS universe, and as a result, the observable might increase nearly exponentially for low axion charge, while it decreases to a vanishing value as one approaches the maximal axion charge allowed by de Sitter space.