Can Before and After Be Superposed?

Can Before and After Be Superposed?Through a quantum-switch experiment, researchers attempt to reveal "indefinite causal order"-a quantum phenomenon involving events in a before-and-after superposition.By Sophia Chen O ver the past century, we have mostly gotten used to the concept of quantum superposition: A particle can exist as a combination of multiple states at once, as famously dramatized by Schrdinger's cat.But quantum mechanics may allow for an even more mind-boggling type of superposition, called "indefinite causal order," where the superposition is not between states but between a sequence of events.A few experiments have delivered hints of indefinite causal order, but they all had several "loopholes"-assumptions that leave room for classical explanations.