Bell experiments – past and future

报告摘要：Local realism is the worldview in which physical properties of objects exist independently of measurement and where physical influences cannot travel faster than the speed of light. Bell’s theorem states that this worldview is incompatible with the predictions of quantum mechanics, as is expressed in Bell’s inequalities. Experimental violations of Bell inequalities are in general vulnerable to so-called “loopholes.” A loophole-free Bell test, closing all major loopholes – the locality, freedom-of-choice, fair-sampling, coincidence-time, and memory loopholes – simultaneously in a single experiment, has been an outstanding goal in the community for decades. In this talk, I will present an experiment that closed all major loopholes simultaneously, using a well-optimized source of entangled photons, rapid setting generation, and highly efficient superconducting detectors [1]. Finally, I will discuss a possible future direction of Bell experiments, namely “cosmic Bell tests” [2].[1] Phys. Rev. Lett. 115, 250401 (2015)[2] Phys. Rev. Lett. 118, 060401 (2017)