Cosmological quantum entanglement

Abstract

Abstract. We review recent literature on the connection between quantum entanglement and cosmology, with an emphasis on the context of expanding universes. We discuss recent theoretical results reporting on the production of entanglement in quantum fields due to the expansion of the underlying spacetime. We explore how these results are affected by the statistics of the field (bosonic or fermionic), the type of expansion (de Sitter or asymptotically stationary), and the coupling to spacetime curvature (conformal or minimal). We then consider the extraction of entanglement from a quantum field by coupling to local detectors and how this procedure can be used to distinguish curvature from heating by their entanglement signature. We review the role played by quantum fluctuations in the early universe in nucleating the formation of galaxies and other cosmic structures through their conversion into classical density anisotropies during and after inflation. We report on current literature attempting to account for this transition in a rigorous way and discuss the importance of entanglement and decoherence in this process. We conclude with some prospects for further theoretical and experimental research in this area. These include extensions of current theoretical efforts, possible future observational pursuits, and experimental analogues that emulate these cosmic effects in a laboratory setting.Cosmological quantum entanglement 2

Entanglement and out-of-equilibrium dynamics in holographic models of de Sitter QFTs

“…To date, there have been a number of proposals for holographic theories living in de Sitter space and other cosmological backgrounds [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. The purpose of the present paper is to study entanglement generated during the cosmological evolution [29][30][31][32][33][34][35][36][37][38]. Entanglement entropy (or geometric entropy) is an important concept and a useful tool in quantum field theories and quantum many body systems, and serves as a probe to characterize states of matter with long range correlations.…”

Continuous variable methods in relativistic quantum information: characterization of quantum and classical correlations of scalar field modes in noninertial frames

“…Traditional streams of investigation in the domain of RQI have included the characterisation of entropy and entanglement between modes of a quantum field as perceived by observers in different states of motion [1,5,6,7,8,9,10,11,12], the production of entangled particles in curved spacetimes and models of the expanding universe [13,14,15], the investigation and applications of spacelike and timelike entanglement extracted from the quantum vacuum [16,17], the modification and generation of entanglement by moving cavities [18,19,20,21], and the analysis of quantum communication protocols such as teleportation and key distribution in noninertial reference frames [22,23,24]. The main theoretical ingredients for RQI ventures are a marriage of quantum field theory on one hand [25], and the formalism of quantum information theory [26] on the other.…”

Casimir forces on atoms in optical cavities

“…Force (in Newtons) due to a uniformly-distributed row of atoms (at positions xn/L = n N +1 ), compared with the value of the Casimir force as given by (32). There are two cases, which are a row of atoms with fixed relative positions xn/L, as given by (30) and the same row of atoms with positions xn fixed with respect to the plate at x = 0, given by (31). In both we choose the parameters L = 0.5 m, Ω = 2πc L resonant with the first field mode and λ = 10 −6 Ω.…”

“…One small caveat is that this simple model encodes the basic features of the light-matter interaction for atomic transitions only in the absence of the exchange of orbital angular momentum [18]. The model has been used in studies of Casimir-Polder forces involving only one conducting plate [19][20][21][22] and is commonly used in studies of quantum field theory in curved spacetimes and relativistic quantum information [30][31][32][33][34][35], as well as in quantum optics (see, e.g., [36]). However, the model does not contain the analog of a diamagnetic field self-interaction term as in (1).…”