# Hong-Ou-Mandel interference between independent III-V on silicon waveguide integrated lasers

## TL;DR

This paper demonstrates Hong-Ou-Mandel interference between weak-coherent pulses from two independent III-V on silicon waveguide lasers, advancing integrated quantum photonics for secure communication.

## Contribution

It reports the first experimental observation of quantum interference between independent integrated lasers on silicon, a key step toward fully integrated quantum key distribution systems.

## Key findings

- Achieved 46 extpm 2 ext% visibility in Hong-Ou-Mandel interference
- Demonstrated integration of III-V lasers on silicon waveguides for quantum applications
- Presents progress toward fully integrated measurement device independent QKD

## Abstract

The versatility of silicon photonic integrated circuits has led to a widespread usage of this platform for quantum information based applications, including Quantum Key Distribution (QKD). However, the integration of simple high repetition rate photon sources is yet to be achieved. The use of weak-coherent pulses (WCPs) could represent a viable solution. For example, Measurement Device Independent QKD (MDI-QKD) envisions the use of WCPs to distill a secret key immune to detector side channel attacks at large distances. Thus, the integration of III-V lasers on silicon waveguides is an interesting prospect for quantum photonics. Here, we report the experimental observation of Hong-Ou-Mandel interference with 46\pm 2% visibility between WCPs generated by two independent III-V on silicon waveguide integrated lasers. This quantum interference effect is at the heart of many applications, including MDI-QKD. Our work represents a substantial first step towards an implementation of MDI-QKD fully integrated in silicon, and could be beneficial for other applications such as standard QKD and novel quantum communication protocols.