Hybrid Quantum Repeater Protocol With Fast Local Processing

TL;DR

This paper introduces an improved hybrid quantum repeater protocol that enhances entanglement distribution efficiency by replacing non-local growth with local growth of cat states and optimizing the process.

Contribution

The paper presents two modifications to a previous quantum repeater protocol, significantly improving its performance by localizing state growth and optimizing entanglement connection methods.

Findings

Modified protocol outperforms original in entanglement distribution efficiency

Local growth of cat states reduces classical communication overhead

Optimized growth procedure enhances overall protocol performance

Abstract

We propose a hybrid quantum repeater protocol combining the advantages of continuous and discrete variables. The repeater is based on the previous work of Brask et al. [Phys. Rev. Lett. 105, 160501 (2010)] but we present two ways of improving this protocol. In the previous protocol entangled single-photon states are produced and grown into superpositions of coherent states, known as two-mode cat states. The entanglement is then distributed using homodyne detection. To improve the protocol, we replace the time-consuming non-local growth of cat states with local growth of single-mode cat states, eliminating the need for classical communication during growth. Entanglement is generated in subsequent connection processes. Furthermore the growth procedure is optimized. We review the main elements of the original protocol and present the two modifications. Finally the two protocols are compared and the modified protocol is shown to perform significantly better than the original protocol.