Causality optional? Testing the "indefinite causal order" superposition

Researchers published a PRX Quantum paper reporting an experiment on indefinite causal order.

The experiment's results differed from Bell-theorem expectations by 18 standard deviations.

Only about 1% of photons were detected, and the team acknowledged loopholes such as photon loss and limited spatial separation.

The authors listed practical applications where the device may outperform causally ordered processes.