Quantum process demonstrates superposition of ordered events

(Phys.org)—In a quantum superposition, a quantum object can be in two incompatible states at the same time, which is famously illustrated by Schrödinger's dead-and-alive cat. Recent research has shown that it's possible to have a superposition not only of incompatible states, but also of incompatible orders of events. We often think of events occurring in a definite chronological order, with event A happening (and causing) event B, or vice versa. But in certain quantum processes, even