# High-visibilty two-photon interference at a telecom wavelength using picosecond regime separated sources

## TL;DR

This paper demonstrates high-visibility two-photon interference at telecom wavelengths using picosecond sources, advancing quantum relay and cryptography applications with improved distance and efficiency.

## Contribution

It introduces a picosecond regime source for two-photon interference at 1550 nm, showing practical benefits over femtosecond and CW regimes for quantum communication.

## Key findings

- Achieved 99% net visibility in two-photon interference.
- Maintained high photon pair rate with standard telecom components.
- Potential for improved quantum relay performance in real-world conditions.

## Abstract

We report on a two-photon interference experiment in a quantum relay configuration using two picosecond regime PPLN waveguide based sources emitting paired photons at 1550 nm. The results show that the picosecond regime associated with a guided-wave scheme should have important repercussions for quantum relay implementations in real conditions, essential for improving both the working distance and the efficiency of quantum cryptography and networking systems. In contrast to already reported regimes, namely femtosecond and CW, it allows achieving a 99% net visibility two-photon interference while maintaining a high effective photon pair rate using only standard telecom components and detectors.