High-Visibility Time-Bin Entanglement for Testing Chained Bell Inequalities

The violation of Bell's inequality requires a well-designed experiment to validate the result. In experiments using energy-time and time-bin entanglement, initially proposed by Franson in 1989, there is an intrinsic loophole due to the high postselection. To obtain a violation in this type of experiment, a chained Bell inequality must be used. However, the local realism bound requires a high visibility in excess of 94.63 percent in the time-bin entangled state. In this work, we show how such a high visibility can be reached in order to violate a chained Bell inequality with 6, 8 and 10 terms.