Quantum Tunneling Is Not Instantaneous, Physicists Show

Quantum tunneling — in which a particle “tunnels” through a seemingly insurmountable barrier — remains a confounding, intuition-defying phenomenon. Now Toronto-based experimental physicists using rubidium atoms to study this effect have measured, for the first time, just how long these atoms spend in transit through a barrier. Their findings appeared in Nature on July 22. The researchers have showed that quantum tunneling is not instantaneous — at least, in one way of thinking about the phenomenon — despite recent headlines that have suggested otherwise. “This is a beautiful experiment,” says Igor Litvinyuk of Griffith University in Australia, who works on quantum tunneling but was not part of this demonstration. “Just to do it is a heroic effort.”


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