Queensland scientists heading up an international team have solved one of the great mysteries of quantum physics: the time it takes for a particle to pass through a barrier.
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Known as “quantum tunnelling” it’s a phenomenon that sees subatomic particles pass through solid but thin barriers such as the wall of an atom.
Professor Robert Sang from Griffith University’s Centre for Quantum Dynamics said the experiments they had conducted over the past three years have confirmed theories that date back to the establishment of quantum physics in the early 20th century.
“I call it extreme science,” Dr Sang said.
“(The theory) has been very controversial, this research does resolve an issue that’s been out in the literature for a long period of time."
Quantum tunnelling has an effect on a number of real-world situations, notably computing, where it is taken into account when designing microchips and flash memory drives.
“There’s no analogue in the real world, and yet we make devices that rely on that,” Dr Sang said.
“But now we’re at the point where the technology and the science has been able to come together enough to make a measurement like this.”
The research team was able to measure the time it takes for a single electron to pass through the atomic wall.
They used an extremely powerful laser to detect the electron on both sides of the barrier, finding it took less than 1.8 attoseconds, which is a billionth of a billionth of a second.
Lead researcher, Associate Professor Igor Litvinyuk, said they used a hydrogen atom for their experiments, which only has one electron to keep the measurements simple.
“We know that the test atom gives us zero delay, so all other delays can be calibrated in respect to that,” Dr Litvinyuk said.
“Now that we’ve tested this atom, we can benchmark this process with other atoms to possibly learn new physics.”
Being able to understand and manipulate quantum tunnelling is one of the things researchers hope will allow them to develop viable quantum computers – extremely powerful computers with exponentially more power than current technology.
More broadly, it is a major leap forward for scientific understand of the quantum realm.
“I would imagine a measurement like this will go into textbooks,” Dr Sang said.
He also said the lab at Griffith University was “the only place in the world” that could have done the experiments, because of the unique array of equipment available.
The research has been published on Tuesday in the journal Nature.
