# Quantum correlations between distant qubits conveyed by large-$S$ spin chains

## TL;DR

This paper demonstrates that quantum correlations, including entanglement, can be generated between distant qubits through interactions with a large-$S$ spin chain, modeled using classical-like equations of motion for the chain's quantum states.

## Contribution

It introduces a method to produce quantum correlations between distant qubits via a large-$S$ spin chain using classical-like dynamics of tensor product states.

## Key findings

- Quantum entanglement can be established without chain length constraints.
- Local interactions with a few chain components suffice to generate correlations.
- Classical-like equations effectively describe the chain's quantum state evolution.

## Abstract

We consider two distant spin-$\frac{1}{2}$ particles (or qubits) and a number of interacting objects, all with the same value $S\gg1$ of their respective spin, distributed on a one-dimensional lattice (or large-$S$ spin chain). The quantum states of the chain are constructed by linearly combining tensor products of single-spin coherent states, whose evolution is determined accordingly, i.e., via classical-like equations of motions. We show that the quantum superposition of the above product states resulting from a local interaction between the first qubit and one spin of the chain evolves so that the second qubit, after having itself interacted with another spin of the chain, can be entangled with the first qubit. Obtaining such outcome does not imply imposing constraints on the length of the chain or the distance between the qubits, which demonstrates the possibility of generating quantum correlations at a distance by means of a macroscopic system, as far as local interactions with just a few of its components are feasible.