Robust Quantum Entanglement Generation and Generation-plus-Storage Protocols with Spin Chains

TL;DR

This paper demonstrates a robust method for generating and storing entangled states in a spin chain with defects, showing high fidelity and resilience to fabrication errors, advancing quantum communication and processing capabilities.

Contribution

It introduces a novel entangling and storage protocol in a spin chain with defects, combining analytical and numerical analysis of robustness against disorder and timing errors.

Findings

Entanglement is robust against up to 10% coupling disorder.

High fidelity entanglement can be achieved with suitable initial states.

The protocol allows for localization and storage of entangled qubits.

Abstract

Reliable quantum communication/processing links between modules are a necessary building block for various quantum processing architectures. Here we consider a spin chain system with alternating strength couplings and containing three defects, that impose three domain walls between topologically distinct regions of the chain. We show that -- in addition to its useful, high fidelity, quantum state transfer properties -- an entangling protocol can be implemented in this system, with optional localisation and storage of the entangled states. We demonstrate both numerically and analytically that, given a suitable initial product-state injection, the natural dynamics of the system produces a maximally entangled state at a given time. We present detailed investigations of the effects of fabrication errors, analyzing random static disorder both in the diagonal and off-diagonal terms of the system Hamiltonian. Our results show that the entangled state formation is very robust against perturbations of up to $\sim10\%$ the weaker chain coupling, and also robust against timing injection errors. We propose a further protocol which manipulates the chain in order to localise and store each of the entangled qubits. The engineering of a system with such characteristics would thus provide a useful device for quantum information processing tasks involving the creation and storage of entangled resources.