Among the weird features of quantum mechanics is the process
known as quantum tunneling, where a subatomic particle overcomes a hurdle that
would be impenetrable in other sorts of physics. Generations of students have
been taught this process with analogies like objects passing through solid
walls, but the time this phenomenon takes has always been unknown. A new research
has set an upper bound on the time it takes, one so short the phenomenon may be
instantaneous, in which case these particles would be traveling faster than the
speed of light.
Tunneling indeed happens so quickly it is hard to detect. Latest
studies have used heavier atoms, necessitating secondary measurements. Dr. Igor Litvinyuk of Griffith University told IFLScience the Australian Attosecond
Science Facility is the single place in the whole world with all three types of
equipment necessary to measure the time it takes electrons to travel from the
grip of hydrogen atoms.
Litvinyuk helped put that combination to use, stating in
Nature that the procedure takes no more than 1.8 attoseconds. An attosecond is
10-18 or a billionth of a billionth of a second. “It’s difficult to appreciate
how short that is, but it takes an electron about a hundred attoseconds to
orbit a nucleus in an atom,” told co-author Professor Robert Sang.
Tunneling time sets a limit on how fast transistors could hypothetically
switch, so having such a short time makes ultra-fast computers more accurate.
Also, Litvinyuk and Sang's value is a ceiling, and they are open to the probability the tunneling is instantaneous. If so, the electron would be passing through a distance in zero time, above the speed of light.
Schematic of the experiment, showing how the turning
electric field creates a clock to measure the timing of the electron's escape.
Sainadh et al./Nature
Litvinyuk told IFLScience the team of scientists are not sure
of such a remarkable claim, but he “cannot see why this is impossible.” He further
said that “this is quantum physics,” a phrase that describes almost any oddity.
“This doesn't essentially mean the superluminous speeds could be used to carry
information.”
0 Comments