Strong violations of locality by testing Bell’s inequality with improved entangled-photon systems

Wang Yao^a), Fan Dai-He^a), Guo Wei-Jie^a), Wei Lian-Fu†^a),^b)

The experimental setup. The lens is used to converge the laser beam, HWPs are used to adjust the polarizations of photons, the BBO crystal down-converts the pump light. The quarter-wave plate (QWP) adjusts the phase position for tomographically reconstructing the density matrix of the generated entangled source. An HWP, a PBS (polarization beam splitter), and an avalanche diode detector form a polarization measurement system of the photon. The filters are introduced to strain the stray light. Finally, the counter shows the coincidence signals of the two detectors.