Causality Constraint on Circuit Complexity from COSMOEFT

Abstract

In this article, we investigate the physical implications of the causality constraint via the effective speed of sound cs(≤1)$c_s(\le 1)$ on Quantum Circuit Complexity (QCC) in the framework of Cosmological Effective Field Theory (COSMOEFT) using the two‐mode squeezed quantum states. This COSMOEFT setup is constructed using the Stnormalü$\ddot{\text{u}}$ckelberg trick with the help of the lowest dimensional operators, which are broken under time diffeomorphism. In this setup, we consider only the contributions from the two derivative terms in the background quasi‐de Sitter metric. Next, we compute the relevant measures of the circuit complexity and their cosmological evolution for different values of cs$c_s$ by following two different approaches, the Nielsen's approach and the Covariance matrix approach. Using this setup, we also compute the Von‐Neumann and the Rényi entropy, which finally establishes an underlying relationship between the entanglement entropy and the circuit complexity. Considering the scale factor and cs$c_s$ as parameters, our analysis of the circuit complexity measures and the entanglement entropy suggests several interesting unexplored features within the window, 0.024≤cs≤1$0.024\le c_s\le 1$, which is supported by both causality and cosmological observation. Finally, we comment on the connection between the circuit complexity, the entanglement entropy and the equilibrium temperature for different cs$c_s$ values lying within the mentioned window.

Galileon inflation evades the no-go for PBH formation in the single-field framework

“…For more details see the refs. [222,253,264], where all of these transformations are explicitly pointed very clearly. In this fashion, a consistent elegant theoretical description of the underlying physical set up is built using the tools and techniques of EFT method by making use of the lowest dimensional Wilsonian operators that are compatible with the underlying symmetries in this context.…”