Observation of eight-photon entanglement

TL;DR

This paper reports the experimental creation of an eight-photon Schrödinger cat state using ultra-bright entangled photon sources, an eight-photon interferometer, and post-selection, demonstrating advanced multi-photon quantum state manipulation.

Contribution

It is the first experimental demonstration of an eight-photon entangled Schrödinger cat state with high fidelity.

Findings

Achieved an eight-photon Schrödinger cat state with fidelity of 0.708

Demonstrated manipulation of eight individual photons

Used ultra-bright sources and post-selection techniques

Abstract

Using ultra-bright sources of pure-state entangled photons from parametric down conversion, an eight-photon interferometer and post-selection detection, we demonstrate the ability to experimentally manipulate eight individual photons and report the creation of an eight-photon Schr\"odinger cat state with an observed fidelity of $0.708 \pm 0.016$.