Near-unit fidelity entanglement distribution using Gaussian communication

TL;DR

This paper presents a scheme for near-perfect entanglement distribution over long distances using Gaussian states and measurements, employing optical squeezing and reamplification to surpass previous benchmarks.

Contribution

The scheme introduces the use of squeezed states and reamplification at repeater stations, enabling high-fidelity entanglement distribution with Gaussian operations.

Findings

Achieves near-unit fidelity over optical attenuation distances.

Uses Gaussian states and measurements, avoiding complex non-Gaussian operations.

Outperforms coherent-state benchmarks in entanglement distribution.

Abstract

We show how to distribute with percentage success probabilities almost perfectly entangled qubit memory pairs over repeater channel segments of the order of the optical attenuation distance. In addition to some weak, dispersive light-matter interactions, only Gaussian state transmissions and measurements are needed for this scheme, which even beats the coherent-state-benchmark for entanglement distribution based on error-free non-Gaussian measurements. This is achieved through two innovations: first, optical squeezed states are utilized instead of coherent states. Secondly, the amplitudes of the bright signal pulses are reamplified at each repeater station. This latter variation is a strategy reminiscent of classical repeaters and would be impossible in single-photon-based schemes.