Bell violation with entangled photons, free of the coincidence-time loophole

Understand

In a local realist world view, physical properties are defined prior to and independent of measurement, and no physical influence can propagate faster than the speed of light.

• Proper experimental violation of a Bell inequality would show that the world cannot be described within local realism.
• Such experiments usually require additional assumptions that make them vulnerable to a number of "loopholes." A recent experiment [Giustina et al, Nature, 2013] violated a Bell inequality without being vulnerable to the detection (or fair-sampling) loophole, therefore not needing the fair-sampling assumption.
• Here we analyze the more subtle coincidence-time loophole, and propose and prove the validity of two different methods of data analysis that avoid it.