Long-distance entanglement in many-body atomic and optical systems

TL;DR

This paper explores long-distance entanglement in many-body quantum systems, proposing physical realizations in ultracold atoms and optical cavities, and demonstrating applications in robust quantum communication and teleportation.

Contribution

It introduces models with perfect and quasi long-distance entanglement and discusses their realization and robustness in experimental setups.

Findings

Models with nonvanishing long-distance entanglement are feasible in ultracold atom lattices.

Engineered optical cavity arrays can optimize entanglement robustness at finite temperatures.

LDE-based quantum teleportation schemes achieve high fidelity and success rates at moderate temperatures.

Abstract

We discuss the phenomenon of long-distance entanglement in the ground state of quantum spin models, its use in high-fidelity and robust quantum communication, and its realization in many-body systems of ultracold atoms in optical lattices and in arrays of coupled optical cavities. We investigate different patterns of site-dependent interaction couplings, singling out two general settings: Patterns that allow for perfect long-distance entanglement (LDE) in the ground state of the system, namely such that the end-to-end entanglement remains finite in the thermodynamic limit, and patterns of quasi long-distance entanglement (QLDE) in the ground state of the system, namely, such such that the end-to-end entanglement vanishes with a very slow power-law decay as the length of the spin chain is increased. We discuss physical realizations of these models in ensembles of ultracold bosonic atoms loaded in optical lattices. We show how, using either suitably engineered super-lattice structures or exploiting the presence of edge impurities in lattices with single periodicity, it is possible to realize models endowed with nonvanishing LDE or QLDE. We then study how to realize models that optimize the robustness of QLDE at finite temperature and in the presence of imperfections using suitably engineered arrays of coupled optical cavities. We finally introduce LDE-based schemes of long-distance quantum teleportation in linear arrays of coupled cavities and show that they allow for high-fidelity and high success rates even at moderately high temperatures.