# Experimental demonstration of switching entangled photons based on the Rydberg blockade effect

## TL;DR

This paper demonstrates a single-photon optical switch using Rydberg blockade to control entangled photons, advancing quantum information processing by enabling interaction control between Rydberg atoms and entangled photon pairs.

## Contribution

It provides the first experimental demonstration of switching entangled photons based on the Rydberg blockade effect, showing effective control of single photons in quantum networks.

## Key findings

- Over 50% photon blocking efficiency achieved
- Switching depends on principal quantum number and gate photon number
- Effective single-photon switch demonstrated with Rydberg blockade

## Abstract

The long-range interaction between Rydberg-excited atoms endows a medium with large optical nonlinearity. Here, we demonstrate an optical switch to operate on a single photon from an entangled photon pair under a Rydberg electromagnetically induced transparency configuration. With the presence of the Rydberg blockade effect, we switch on a gate field to make the atomic medium nontransparent thereby absorbing the single photon emitted from another atomic ensemble via the spontaneous four-wave mixing process. In contrast to the case without a gate field, more than 50% of the photons sent to the switch are blocked, and finally achieve an effective single-photon switch. There are on average 1-2 gate photons per effective blockade sphere in one gate pulse. This switching effect on a single entangled photon depends on the principal quantum number and the photon number of the gate field. Our experimental progress is significant in the quantum information process especially in controlling the interaction between Rydberg atoms and entangled photon pairs.