# Experimental quantum repeater without quantum memory

## TL;DR

This paper demonstrates an all-photonic quantum repeater using linear optics, achieving an 89% higher entanglement rate without requiring quantum memory, thus offering a promising alternative for scalable quantum networks.

## Contribution

The first experimental realization of an all-photonic quantum repeater using linear optics and photonic graph states, eliminating the need for quantum memory.

## Key findings

- Achieved 89% enhancement in entanglement-generation rate.
- Implemented a 2-by-2 parallel all-photonic quantum repeater.
- Demonstrated feasibility of memory-free quantum repeaters.

## Abstract

Quantum repeaters -- important components of a scalable quantum internet -- enable the entanglement to be distributed over long distances. The standard paradigm for a quantum repeater relies on a necessary demanding requirement of quantum memory. Despite significant progress, the limited performance of quantum memory makes practical quantum repeaters still a great challenge. Remarkably, a proposed all-photonic quantum repeater avoids the need for quantum memory by harnessing the graph states in the repeater nodes. Here we perform an experimental demonstration of an all-photonic quantum repeater using linear optics. By manipulating a 12-photon interferometer, we implement a 2-by-2 parallel all-photonic quantum repeater, and observe an 89% enhancement of entanglement-generation rate over the standard parallel entanglement swapping. These results open a new way towards designing repeaters with efficient single-photon sources and photonic graph states, and suggest that the all-photonic scheme represents an alternative path -- parallel to that of matter-memory-based schemes -- towards realizing practical quantum repeaters.