Physics World October 2025

Causal chaos: what happens when cause and effect are in a quantum superposition

In the latest of our series of articles about weird quantum effects, Hamish Johnston examines the notion of “indefinite causal order”, which is challenging our understanding of cause and effect. Also this month, there’s an interview with Nobel-prize-winning physicist William Phillips, along with a panel discussion on how quantum technology is boosting quantum fundamentals. Finally, don’t miss our look at careers for physicists in intelligence and cyber security at GCHQ.

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