The Rise of Cosmological Complexity: Saturation of Growth and Chaos

Abstract

We compute the circuit complexity of scalar curvature perturbations on FLRW cosmological backgrounds with fixed equation of state $w$ using the language of squeezed vacuum states. Backgrounds that are accelerating and expanding, or decelerating and contracting, exhibit features consistent with chaotic behavior, including linearly growing complexity. Remarkably, we uncover a bound on the growth of complexity for both expanding and contracting backgrounds $\lambda \le \sqrt{2}|H|$, similar to other bounds proposed independently in the literature. The bound is saturated for expanding backgrounds with an equation of state more negative than $w=-5/3$, and for contracting backgrounds with an equation of state larger than $w=1$. For expanding backgrounds that preserve the null energy condition, de Sitter space has the largest rate of growth of complexity (identified as the Lyapunov exponent), and we find a scrambling time that is similar to other estimates up to order one factors.

19 pages, 9 figures

References in corpus (4)

• Complexity and Shock Wave Geometries
• Quantum Computation as Geometry
• Liouville Action as Path-Integral Complexity: From Continuous Tensor Networks to AdS/CFT
• Inflationary Perturbations: the Cosmological Schwinger Effect

Cited by in corpus (3)

• Quantum Circuit Complexity of Primordial Perturbations
• Chaos and Complexity from Quantum Neural Network: A study with Diffusion Metric in Machine Learning
• The Cosmological OTOC: A New Proposal for Quantifying Auto-Correlated Random Non-Chaotic Primordial Fluctuations