# Field test of entanglement swapping over 100-km optical fiber with independent 1-GHz-clock sequential time-bin entangled photon-pair sources

## TL;DR

This paper demonstrates long-distance entanglement swapping over 100 km of optical fiber using independent high-rate photon sources, advancing quantum network capabilities in real-world environments.

## Contribution

It presents the first field test of entanglement swapping over 100 km with independent 1-GHz-clock time-bin photon sources in complex fiber environments.

## Key findings

- Successful entanglement swapping over 100 km fiber link
- Use of automatic stability controls for long-distance quantum communication
- Verification of feasibility for future quantum networks

## Abstract

Realizing long distance entanglement swapping with independent sources in the real-world condition is important for both future quantum network and fundamental study of quantum theory. Currently, demonstration over a few of tens kilometer underground optical fiber has been achieved. However, future applications demand entanglement swapping over longer distance with more complicated environment. We exploit two independent 1-GHz-clock sequential time-bin entangled photon-pair sources, develop several automatic stability controls, and successfully implement a field test of entanglement swapping over more than 100-km optical fiber link including coiled, underground and suspended optical fibers. Our result verifies the feasibility of such technologies for long distance quantum network and for many interesting quantum information experiments.