Deterministic distribution of W-class states in quantum networks

TL;DR

This paper presents methods for the deterministic distribution of non-symmetric W-class entangled states in quantum networks, enabling reliable quantum communication protocols despite noise.

Contribution

It introduces protocols for deterministic distribution of $W_{ ext{mod}}$ states via a central node, analyzing their performance under noise and comparing with non-central distribution methods.

Findings

Protocols achieve high fidelity in ideal conditions.

Performance degrades with noise, but remains superior to non-central methods.

Distribution fidelity depends on noise type and strength.

Abstract

Multipartite entangled states possess a number of non-intuitive properties, making them a useful resource for various quantum information-processing tasks. The three-qubit W-state is one such example where every state is robust to single-qubit loss. However, this state is not suitable for deterministic distribution, and deterministic communication protocols. Here, we focus on the distribution of a non-symmetric version of such states, namely $W_{\mathrm{mod}}$ states. These states belong to the W-class, and have one ebit of entanglement across a specific bipartition, enabling deterministic teleportation and superdense coding. In particular, we describe a few protocols through which these multipartite entangled states can be distributed {\it deterministically} in a quantum network by first preparing them locally in a central node and then transmitting individual qubits to the end nodes. We analyse the performance of these protocols based on the fidelity of the final distributed state, considering all types of noises that can act during the distribution. Finally, we compare the performance of the protocols to the case where the distribution is performed without any central node.