# Microscale generation of entangled photons without momentum conservation

## TL;DR

This paper demonstrates the first generation of entangled photon pairs in an ultra-thin lithium niobate wafer without momentum conservation, revealing a new broadband source with tight spatial and temporal correlations.

## Contribution

It introduces a novel method for entangled photon generation via non-phase matched SPDC in ultra-thin lithium niobate, bypassing momentum conservation constraints.

## Key findings

- Non-phase matched SPDC produces ultra-broadband entangled photons.
- Emission exhibits tight spatial and temporal correlations.
- Potential for new quantum photonics applications.

## Abstract

We report, for the first time, the generation of entangled photon pairs via type-0 spontaneous parametric down conversion in an ultra-thin wafer of lithium niobate in which momentum between the pump photon and daughter photons is not conserved. The characteristics of the emission are investigated using several techniques. We find that non-phase matched SPDC is a promising source of ultra-broadband two photon radiation that exhibits remarkably tight correlation widths in both the spatial and temporal domains.