Among the strange features of quantum mechanics is the phenomenon known as quantum tunneling, where a subatomic particle overcomes a barrier that would be impassable in other sorts of physics. Generations of physics students have been taught this phenomenon with analogies like objects passing through solid walls, but the time this process takes has always been a mystery. A new study has set an upper bound on the time it takes, one so short the process may be instantaneous, in which case these particles would be exceeding the speed of light.
Tunneling certainly happens so quickly it is hard to measure. Recent efforts have used heavier atoms, necessitating indirect measurements. Dr Igor Litvinyuk of Griffith University told IFLScience the Australian Attosecond Science Facility is the only place in the world with all three types of equipment required to measure the time it takes electrons to tunnel from the grip of hydrogen atoms.
Litvinyuk helped put that combination to use, reporting in Nature that the process takes no more than 1.8 attoseconds. An attosecond is 10-18 or a billionth of a billionth of a second. “It’s hard to appreciate how short that is, but it takes an electron about a hundred attoseconds to orbit a nucleus in an atom,” said co-author Professor Robert Sang in a statement.
Tunneling time sets a limit on how fast transistors could theoretically switch, so having such a short time makes ultra-fast computers more realistic.
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