Experimental demonstration of a heralded entanglement source

TL;DR

This paper demonstrates a heralded entanglement source using a conditioned detection scheme that improves efficiency and fidelity, advancing quantum information processing and optical quantum computing.

Contribution

It introduces a robust, event-ready entanglement source with enhanced efficiency and fidelity, utilizing a flexible setup based on spontaneous parametric down-conversion.

Findings

Achieved over 87% fidelity in entangled photon states.

Realized a 45% state preparation efficiency.

Demonstrated a flexible scheme adaptable with different beamsplitters.

Abstract

The heralded generation of entangled states is a long-standing goal in quantum information processing, because it is indispensable for a number of quantum protocols. Polarization entangled photon pairs are usually generated through spontaneous parametric down-conversion, but the emission is probabilistic. Their applications are generally accompanied by post-selection and destructive photon detection. Here, we report a source of entanglement generated in an event-ready manner by conditioned detection of auxiliary photons. This scheme benefits from the stable and robust properties of spontaneous parametric down-conversion and requires only modest experimental efforts. It is flexible and allows the preparation efficiency to be significantly improved by using beamsplitters with different transmission ratios. We have achieved a fidelity better than 87% and a state preparation efficiency of 45% for the source. This could offer promise in essential photonics-based quantum information tasks, and particularly in enabling optical quantum computing by reducing dramatically the computational overhead.