Circumventing defective components in linear optical interferometers

A crucial challenge to the scaling up of linear optical interferometers is the presence of defective optical components resulting from inevitable imperfections in fabrication and packaging. This work presents a method for circumventing such defective components including lossy modes and unresponsive phase shifters and beam-splitters. The method allows for using universal linear optical interferometers with such defects as smaller universal interferometers. The method presented here tolerates remarkably high defect rates in constructing linear optical interferometers, thus bringing closer to reality the possibility of obtaining quantum advantage with linear optics.