# Spin chains for two-qubit teleportation

## TL;DR

This paper demonstrates that a spin-1/2 chain with XX interactions can naturally generate two Bell pairs at its ends, enabling high-fidelity two-qubit teleportation through its intrinsic dynamics.

## Contribution

It introduces a method to generate two Bell pairs using the natural dynamics of a single spin chain, facilitating two-qubit teleportation with high fidelity.

## Key findings

- High-fidelity two-qubit teleportation is achievable with weakly coupled end pairs.
- An effective Hamiltonian accurately models the system's dynamics.
- Predefined times yield states close to two Bell pairs with minimal infidelity.

## Abstract

Generating high-quality multi-particle entanglement between communicating parties is the primary resource in quantum teleportation protocols. To this aim, we show that the natural dynamics of a single spin chain is able to sustain the generation of two pairs of Bell states - possibly shared between a sender and a distant receiver - which can in turn enable two-qubit teleportation. In particular, we address a spin-1/2 chain with XX interactions, connecting two pairs of spins located at its boundaries, playing the roles of sender and receiver. In the regime where both end pairs are weakly coupled to the spin chain, it is possible to generate at predefinite times a state that has vanishing infidelity with the product state of two Bell pairs, thereby providing nearly unit fidelity of teleportation. We also derive an effective Hamiltonian via a second-order perturbation approach that faithfully reproduces the dynamics of the full system.