Information Engines

June 25, 2021 1:11 AM

World's fastest information-fueled engine designed by university researchers - "The development of this engine, which converts the random jiggling of a microscopic particle into stored energy, is [informing] researchers' understanding of how to rapidly and efficiently convert information into 'work.'"

Engines of this type were first proposed over 150 years ago, but actually making them has only recently become possible... The information engine designed by SFU researchers consists of a microscopic particle immersed in water and attached to a spring which, itself, is fixed to a movable stage. Researchers then observe the particle bouncing up and down due to thermal motion.

"When we see an upward bounce, we move the stage up in response," explains lead author and Ph.D. student Tushar Saha. "When we see a downward bounce, we wait. This ends up lifting the entire system using only information about the particle's position."

Repeating this procedure, they raise the particle "a great height, and thus store a significant amount of gravitational energy," without having to directly pull on the particle.

Saha further explains that "in the lab, we implement this engine with an instrument known as an optical trap, which uses a laser to create a force on the particle that mimics that of the spring and stage."

How Maxwell's Demon Continues to Startle Scientists - "The thorny thought experiment has been turned into a real experiment — one that physicists use to probe the physics of information."

Then in the 21st century, with the thought experiment solved, the real experiments began. “The most important development is we can now realize Maxwell’s demon in laboratories,” said Sagawa.

In 2007 scientists used a light-powered gate to demonstrate the idea of Maxwell’s demon in action; in 2010, another team devised a way to use the energy produced by the demon’s information to coax a bead uphill; and in 2016 scientists applied the idea of Maxwell’s demon to two compartments containing not gas, but light.

“We switched the roles of matter and light,” said Vlatko Vedral, a physicist at the University of Oxford and one of the study’s co-authors. The researchers were ultimately able to charge a very small battery.

also btw...

• Breaking Heisenberg: Evading the Uncertainty Principle in Quantum Physics - "Researchers were able to simultaneously measure the position and the momentum of the two drumheads — which should not be possible according to the Heisenberg uncertainty principle. Breaking the rule allows them to be able to characterize extremely weak forces driving the drumheads... In the future, the research group will use these ideas in laboratory tests aiming at probing the interplay of quantum mechanics and gravity."
• Vibrating drumheads are entangled quantum mechanically - "In the measurement phase, the researchers measured the position and momenta of the two membranes at the same instant. After 10,000 repetitions, the researchers found that they were correlated so well that the two membranes must be entangled, as otherwise the predictability of the position and momenta of one membrane from those of the other would violate Heisenberg's uncertainty principle. 'The position of one and the position of the other agrees much better than the diameter of a proton', says team member Shlomi Kotler, now at the Hebrew University of Jerusalem."
• Physicists induce motionless quantum state in largest object yet - "Most of the time, these experiments are done with clouds of millions of atoms, but the new test was performed on a 10-kg (22-lb) object that contains almost an octillion atoms. Strangely enough, that 'object' isn't just one thing itself but the combined motion of four different objects, with a mass of 40 kg (88 lb) each."

The researchers conducted the experiment at LIGO, a huge facility famous for detecting gravitational waves as they wash over Earth. It does this by beaming lasers down two 4-km (2.5-mile) tunnels, and bouncing them back with mirrors – and those mirrors were the objects that the new study cooled to a motional ground state.

Cooling atoms is simple in principle – you just have to counter their motion with an equal and opposite force. But that requires measuring their motion extremely precisely, and complicating things even further, the very act of measuring them can exert a new force on them.

Intriguingly, the new study used this to the team’s advantage. The photons of light in LIGO’s lasers exert tiny bumps on the mirrors as they bounce off, and these disturbances can be measured in later photons. Since the beams are constant, the scientists have plenty of data about the motions of the atoms in the mirrors – meaning they can then design the perfect counteracting forces.

To do so, the researchers attached electromagnets to the back of each mirror, which reduced their collective motion almost to the motional ground state. The mirrors moved less than one-thousandth the width of a proton, essentially cooling down to a crisp 77 nanokelvins – a hair above absolute zero.

• Researchers see atoms at record resolution - "The resolution is so fine-tuned, the only blurring that remains is the thermal jiggling of the atoms themselves... Ptychography works by scanning overlapping scattering patterns from a material sample and looking for changes in the overlapping region... The detector is slightly defocused, blurring the beam, in order to capture the widest range of data possible. This data is then reconstructed via complex algorithms, resulting in an ultraprecise image with picometer (one-trillionth of a meter) precision."

"With these new algorithms, we're now able to correct for all the blurring of our microscope to the point that the largest blurring factor we have left is the fact that the atoms themselves are wobbling, because that's what happens to atoms at finite temperature," Muller said. "When we talk about temperature, what we're actually measuring is the average speed of how much the atoms are jiggling."

"Reshuffling an already shuffled deck changes nothing in expectation but everything in fact." --@interfluidity

posted by kliuless (11 comments total)

This has a name: The Nefastis Box

a-and give the importance of light to all this, not to mention demons, it is wonderful nominative determinism that one of the scientists quoted in the main article is ... Joseph Lucero.
posted by chavenet at 2:51 AM on June 25, 2021 [5 favorites]

While I do not in any way fully understand most of what I'm reading in the various links, it all still sounds utterly amazing and fascinating. Thanks!
posted by Thorzdad at 4:02 AM on June 25, 2021

The point of Maxwell's Demon, as I understood it, was that it couldn't exist - if you could actually gain useful energy by watching and responding to the random movements of particles, that would violate the laws of thermodynamics.

So my understanding is that you can do this, but it will always turn out that the system that does the watching and responding to make it happen will consume more energy than you can extract from the process.

You can have the demon farm particles for you, but the demon needs to be paid, and you'll never break even.
posted by automatronic at 5:12 AM on June 25, 2021 [6 favorites]

I thought late stage capitalism already solved that problem?
posted by fairmettle at 5:28 AM on June 25, 2021 [1 favorite]

the demon needs to be paid

Sounds like a job for cryptocurrency.
posted by flabdablet at 5:40 AM on June 25, 2021 [1 favorite]

Indeed, Maxwell's demon would probably accept payment in cryptocurrency, as it could be confident that sufficient energy is being wasted elsewhere that entropy still triumphs in the deal.
posted by automatronic at 5:44 AM on June 25, 2021 [15 favorites]

Honestly the little nugget of "Maxwell's demon only accepts crypto" is juicy enough to make a short story or something out of, if someone does plz link
posted by lazaruslong at 6:01 AM on June 25, 2021 [2 favorites]

Maxwell’s Demon was initially a thought experiment, the conclusion being that information is literally equivalent to energy, so saying “all we need is information to get free energy” is a nonsense statement, and would be better phrased as “we can convert information energy to other kinds of energy”.

The point of these experiments is that Maxwell’s Demon is no longer a thought experiment. It’s just a regular real-life experiment now.
posted by notoriety public at 7:21 AM on June 25, 2021 [3 favorites]

Researchers were able to simultaneously measure the position and the momentum of the two drumheads — which should not be possible

Can someone elaborate what broke here?
posted by Reasonably Everything Happens at 11:58 AM on June 25, 2021

This has strong Heart of Gold energy to me.
posted by Tesseractive at 1:49 PM on June 25, 2021 [4 favorites]

Reasonably Everything Happens: "Researchers were able to simultaneously measure the position and the momentum of the two drumheads — which should not be possible

Can someone elaborate what broke here?"

The uncertainty principle says that we cannot measure the position (x) and the momentum (p) of a particle with absolute precision. The more accurately we know one of these values, the less accurately we know the other.
posted by chavenet at 10:36 AM on June 26, 2021