Bell nonlocality plays a fundamental role in quantum theory. Numerous tests of the Bell inequality have been reported since the ground-breaking discovery of the Bell theorem. Up to now, however, most discussions of the Bell scenario have focused on a single pair of entangled particles distributed to only two separated observers. Recently, it has been shown surprisingly that multiple observers can share the nonlocality present in a single particle from an entangled pair using the method of weak measurements [Phys. Rev. Lett. 114, 250401 (2015)]. Here we report an observation of double CHSH-Bell inequality violations for a single pair of entangled photons with strength continuous-tunable optimal weak measurements in photonic system for the first time. Our results shed new light on the interplay between nonlocality and quantum measurements and our design of weak measurement protocol may also be significant for important applications such as unbounded randomness certification and quantum steering.

张永生, 于中国科学技术大学物理系获得学士和博士学位, 毕业后一直在中国科学技术大学物理学院任教, 期间2013-2014年在美国德克萨斯大学达拉斯分校访问。曾获国家自然科学二等奖(第五完成人), 福建省自然科学二等奖(第二完成人), 入选2005年教育部新世纪优秀人才计划, 2009年获中科院卢嘉锡青年人才奖。在Phys. Rev. Lett., Phys. Rev. A等期刊上发表论文100余篇, 被SCI他引1300余次。长期从事量子光学方向的科研和教学。