# Generation of a frequency-degenerate four-photon entangled state using a silicon nanowire

## TL;DR

This paper demonstrates the generation of frequency-degenerate four-photon entangled states on a silicon nanowire chip, enabling scalable quantum information processing with high-quality entangled photon sources.

## Contribution

It introduces a novel on-chip method for creating indistinguishable multi-photon entangled states using a silicon nanowire and a Sagnac loop, advancing integrated quantum photonics.

## Key findings

- Successful generation of four-photon entangled states
- States enable phase super-resolution
- Method is compact and scalable

## Abstract

Integrated photonics is becoming an ideal platform for generating two-photon entangled states with high brightness, high stability and scalability. This high brightness and high quality of photon pair sources encourages researchers further to study and manipulate multi-photon entangled states. Here, we experimentally demonstrate frequency-degenerate four-photon entangled state generation based on a single silicon nanowire 1 cm in length. The polarization encoded entangled states are generated with the help of a Sagnac loop using additional optical elements. The states are analyzed using quantum interference and state tomography techniques. As an example, we show that the generated quantum states can be used to achieve phase super-resolution. Our work provides a method for preparing indistinguishable multi-photon entangled states and realizing quantum algorithms in a compact on-chip setting.