Quantum teleportation in expanding FRW universe

TL;DR

The paper addresses how FRW spacetime expansion affects quantum teleportation between comoving observers by tying the protocol's fidelity to cosmological Bogoliubov mode mixing. It combines a field-theoretic description of a massless scalar field in FRW, Bogoliubov transformations, and a continuous-variable teleportation framework using a two-mode squeezed vacuum. The authors derive analytic expressions for $|\beta_k|^2$ in power-law and de Sitter backgrounds and show that the teleportation fidelity $F(k)$ degrades relative to the Minkowski baseline $F_{\text{Mink}} = \frac{1}{1+e^{-2r}}$, with degradation strongest in de Sitter and weakest in radiation-dominated eras. The covariance-matrix treatment corroborates the results and highlights the role of spacetime expansion as an effective noise source for quantum information processing in cosmological settings.

Abstract

We investigate the process of quantum teleportation in an expanding universe modeled by Friedmann-Robertson-Walker spacetime, focusing on two cosmologically relevant scenarios: a power-law expansion and the de Sitter universe. Adopting a field-theoretical approach, we analyze the quantum correlations between two comoving observers who share an entangled mode of a scalar field. Using the Bogoliubov transformation, we compute the teleportation fidelity and examine its dependence on the expansion rate, initial entanglement, and the mode frequency. Our findings indicate that spacetime curvature and the underlying cosmological background significantly affect the efficiency of quantum teleportation, particularly through mode mixing and vacuum structure. We also compare our results with the flat Minkowski case to highlight the role of cosmic expansion in degrading or preserving quantum information.

Figures (2)

• Figure 1: Teleportation fidelity $F_{\text{dS}}(k)$ in de Sitter spacetime for several values of the Hubble parameter $H$. Larger $H$ increases Gibbons--Hawking particle production, which enhances the Bogoliubov coefficient $\beta_k$ and consequently lowers the fidelity. The limit $H \to 0$ approaches the flat-spacetime baseline.
• Figure 2: Teleportation fidelity as a function of $k$ in a matter-dominated FRW universe. The figure shows that the fidelity gradually increases with $k$ and asymptotically approaches a saturation value.