Scientists bring ‘nonsensical’ quantum physics into the real world for the first time

By freezing a drum just large enough to be seen by the naked eye to close to absolute zero, researchers were able to see glimpses of quantum effects normally confined to the world of atoms

Ian Johnston
Science Correspondent
@montaukian
Thursday 12 January 2017 19:38
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The baffling world of 'Alice in Wonderland' may be closer to reality than originally thought, according to the research
The baffling world of 'Alice in Wonderland' may be closer to reality than originally thought, according to the research

In the Alice in Wonderland world of the atomically small, things can be in two places at once, merely looking at a particle can alter a twin on the other side of the universe apparently instantaneously, and theoretical cats can be both alive and dead.

Certainty is also somehow replaced by chance, an idea that once moved a somewhat vexed Albert Einstein to famously say: “God doesn’t play dice with the universe.”

Such strange, almost magical effects have always been confined to the world of photons and atoms – until now.

In the journal Nature, scientists at the US National Institute of Standards and Technology (NIST) in Colorado reported the first “glimpses” of quantum effects, as they are known, happening on a scale just large enough to be seen by the human eye.

It is a breakthrough that could have significant implications for attempts to create quantum computers that are many millions of times faster than the current machines.

One of the researchers, Dr John Teufel, told the Independent: “I think we’re in an extremely exciting time where this technology we have available gives us access to things people have been talking about as thought experiments for decades.

“Just now what’s exciting is we can go into the laboratory and actually witness these quantum effects.”

The way they achieved this sounds almost as strange as the quantum mechanics itself.

A tiny aluminium drum, about the diameter of a “very skinny hair”, was cooled to only fractionally above absolute zero, which at minus 273.15 degrees Celsius or zero Kelvin is the lowest possible temperature, using microwave light.

While shining a light on something might normally be expected to heat it up, in this case it actually "steals" energy from the drum as it vibrates.

Previously there was thought to be a limit to how far this cooling could go, because light photons hitting an object also have a heating effect.

But the NIST team were able to “squeeze” the light, Dr Teufel said, so “all the photons know about each other”.

This enabled them to cool the drum to a point that was previously believed to be theoretically impossible.

It is hard to express the temperature in Celsius because it is so cold, but standard microwave-cooling method enabled the researcher to get the drum to within a few hundred microKelvin of absolute zero or 0.4 quanta. And the new light-squeezing technique then enabled them to reduce the temperature further to just 0.19 quanta.

At this temperature, Dr Teufel said they were able to observe “glimpses of quantum effects”.

“It makes some of the quantum things more visible and more prevalent,” he said.

In 2004, scientists in Austria reported they had teleported photons across the Danube River.

But now Dr Teufel and his colleagues are starting to dream about teleporting something large enough to be seen.

“You could imagine doing experiments where you could teleport something into the vibrations of the drum,” he said.

Other impossible-sounding quantum effects may also become visible.

“What we’d like to do is put these vibrations of the drum in a quantum state, so it’s in two places at once – it’s vibrating up and, at the same time, it’s vibrating down,” Dr Teufel said.

“It sounds weird to all of us.”

The research should help establish the point at which the rules of quantum mechanics are replaced by more ordinary physics and how the odd rules of the very small fit into those governing the movements of stars and planets.

“The rules of quantum mechanics have been verified over and over,” Dr Teufel said.

“We’ve seen it all the time in microscopic systems. The idea of how, why, cannot it happen with larger objects is more a question of trying to figure out what we don’t understand about the system.

“For me personally, the excitement of the field is to keep scaling up to larger and larger scales.

“In principle there’s no reason why that [drum] couldn’t be 10 times bigger.”

But could it be dangerous to unleash the crazy world of quantum mechanics on a large scale?

“I don’t think so,” Dr Teufel said.

“The reason I say that is the very fact you have to work so hard to witness these things means these quantum effects are extremely delicate and fragile.

“If they start to interact with the outside world in any way, it immediately makes things go back to the boring classical behaviour.

“It’s powerful but not dangerous.”

Quantum computers appear to be the most immediate practical application of the research. These could increase the current processing power by some 100 million times.

Normal computers store information as a series of ones and zeroes.

But, as Dr Teufel explained, “the whole magic of quantum computing is it doesn’t have to be zero or one, it could be zero and one”.

Such ideas are difficult to comprehend, but sometimes one simply must suspend disbelief.

Particle physicist Robert Gilmore perhaps put it best in his 1995 book Alice in Quantumland: “However nonsensical quantum mechanics may at times appear to us, that seems to be the way that Nature wants it – and so we have to play along.”

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