Quantum Time Chaos: New Test Supports Indefinite Causal Order
A Vienna team extends Bell-test ideas to indefinite causal order, using entangled photons arranged so that the sequence A→B or B→A depends on polarization. The observed correlations differ from local-hidden-variable predictions by 18 standard deviations, suggesting quantum processes can exist in a superposition of temporal orders. However, notable loopholes remain (photon loss, limited separation) and further experiments are needed to close them, though the work points toward broader applications of time-uncertain quantum processes.