High-fidelity entanglement purification using chains of atoms and optical cavities

TL;DR

This paper presents an improved entanglement purification scheme using chains of atoms and optical cavities, achieving near-perfect fidelity without complex gate operations, advancing long-distance quantum communication.

Contribution

It introduces an enhanced protocol with additional entanglement steps and optimized laser control, significantly increasing output fidelity in quantum repeaters.

Findings

Achieves almost unit output fidelity in entanglement purification.

Reduces complexity by avoiding controlled-NOT gates.

Provides a feasible approach for long-distance quantum communication.

Abstract

In our previous paper [Phys. Rev. A 84, 042303 (2011)], we proposed an efficient scheme to purify dynamically a bipartite entangled state using short chains of atoms coupled to high-finesse optical cavities. In contrast to conventional entanglement purification protocols, we avoid controlled-NOT gates and thus reduce complicated pulse sequences and superfluous qubit operations. In this paper, we significantly improve the output fidelity of remotely entangled atoms by introducing one additional entanglement protocol in each of the repeater nodes and by optimizing the laser beams required to control the entire scheme. Our improved distillation scheme yields an almost unit output fidelity that, together with the entanglement distribution and swapping, opens an attractive route towards an efficient and experimentally feasible quantum repeater for long-distance quantum communication.