Quantum nonlocality lies at the heart of quantum information and quantum physics. It has been regarded as essential resource for device-independent quantum information processing in recent years. Most experiments of nonlocality are performed using a photonic system. However, until now, photonic experiments of nonlocality have involved at most four photons. The group of Prof. LI Chuanfeng and HUANG Yunfeng from Key Lab of Quantum Information upgrades their beamlike entangled photon source to sandwichlike entangled photon source, which is more symmetric. The coincidence rate of this entangled photon source is 0.29, with entanglement fidelity up to 99% and brightness up to 2000 pairs/mW/s. Based on above improvement, for the first time, they experimentally demonstrate the six-photon quantum nonlocality in an all-versus-nothing manner based on a high-fidelity (88.4%) six-photon Greenberger-Horne-Zeilinger state. The experiment pushes multiphoton nonlocality studies forward to the six-photon region and might provide a larger photonic system for device independent quantum information protocols. The result is published in Physical Review Letters as an Editors’ Suggestion paper.
Illustration of sandwichlike entangled photon source
Link of the paper: http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.115.260402