Tag Archives: fire

Quantum back action and devil’s play

I always appreciate a reference to James Clerk Maxwell’s demon thought experiment (you can find out about it in the Maxwell’s demon Wikipedia entry). This time it comes from physicist  Kater Murch in a July 23, 2018 Washington University in st. Louis (WUSTL) news release (published July 25, 2018 on EurekAlert) written by Brandie Jefferson (offering a good explanation of the thought experiment and more),

Thermodynamics is one of the most human of scientific enterprises, according to Kater Murch, associate professor of physics in Arts & Sciences at Washington University in St. Louis.

“It has to do with our fascination of fire and our laziness,” he said. “How can we get fire” — or heat — “to do work for us?”

Now, Murch and colleagues have taken that most human enterprise down to the intangible quantum scale — that of ultra low temperatures and microscopic systems — and discovered that, as in the macroscopic world, it is possible to use information to extract work.

There is a catch, though: Some information may be lost in the process.

“We’ve experimentally confirmed the connection between information in the classical case and the quantum case,” Murch said, “and we’re seeing this new effect of information loss.”

The results were published in the July 20 [2018] issue of Physical Review Letters.

The international team included Eric Lutz of the University of Stuttgart; J. J. Alonzo of the University of Erlangen-Nuremberg; Alessandro Romito of Lancaster University; and Mahdi Naghiloo, a Washington University graduate research assistant in physics.

That we can get energy from information on a macroscopic scale was most famously illustrated in a thought experiment known as Maxwell’s Demon. [emphasis mine] The “demon” presides over a box filled with molecules. The box is divided in half by a wall with a door. If the demon knows the speed and direction of all of the molecules, it can open the door when a fast-moving molecule is moving from the left half of the box to the right side, allowing it to pass. It can do the same for slow particles moving in the opposite direction, opening the door when a slow-moving molecule is approaching from the right, headed left. ­

After a while, all of the quickly-moving molecules are on the right side of the box. Faster motion corresponds to higher temperature. In this way, the demon has created a temperature imbalance, where one side of the box is hotter. That temperature imbalance can be turned into work — to push on a piston as in a steam engine, for instance. At first the thought experiment seemed to show that it was possible create a temperature difference without doing any work, and since temperature differences allow you to extract work, one could build a perpetual motion machine — a violation of the second law of thermodynamics.

“Eventually, scientists realized that there’s something about the information that the demon has about the molecules,” Murch said. “It has a physical quality like heat and work and energy.”

His team wanted to know if it would be possible to use information to extract work in this way on a quantum scale, too, but not by sorting fast and slow molecules. If a particle is in an excited state, they could extract work by moving it to a ground state. (If it was in a ground state, they wouldn’t do anything and wouldn’t expend any work).

But they wanted to know what would happen if the quantum particles were in an excited state and a ground state at the same time, analogous to being fast and slow at the same time. In quantum physics, this is known as a superposition.

“Can you get work from information about a superposition of energy states?” Murch asked. “That’s what we wanted to find out.”

There’s a problem, though. On a quantum scale, getting information about particles can be a bit … tricky.

“Every time you measure the system, it changes that system,” Murch said. And if they measured the particle to find out exactly what state it was in, it would revert to one of two states: excited, or ground.

This effect is called quantum backaction. To get around it, when looking at the system, researchers (who were the “demons”) didn’t take a long, hard look at their particle. Instead, they took what was called a “weak observation.” It still influenced the state of the superposition, but not enough to move it all the way to an excited state or a ground state; it was still in a superposition of energy states. This observation was enough, though, to allow the researchers track with fairly high accuracy, exactly what superposition the particle was in — and this is important, because the way the work is extracted from the particle depends on what superposition state it is in.

To get information, even using the weak observation method, the researchers still had to take a peek at the particle, which meant they needed light. So they sent some photons in, and observed the photons that came back.

“But the demon misses some photons,” Murch said. “It only gets about half. The other half are lost.” But — and this is the key — even though the researchers didn’t see the other half of the photons, those photons still interacted with the system, which means they still had an effect on it. The researchers had no way of knowing what that effect was.

They took a weak measurement and got some information, but because of quantum backaction, they might end up knowing less than they did before the measurement. On the balance, that’s negative information.

And that’s weird.

“Do the rules of thermodynamics for a macroscopic, classical world still apply when we talk about quantum superposition?” Murch asked. “We found that yes, they hold, except there’s this weird thing. The information can be negative.

“I think this research highlights how difficult it is to build a quantum computer,” Murch said.

“For a normal computer, it just gets hot and we need to cool it. In the quantum computer you are always at risk of losing information.”

Here’s a link to and a citation for the paper,

Information Gain and Loss for a Quantum Maxwell’s Demon by M. Naghiloo, J. J. Alonso, A. Romito, E. Lutz, and K. W. Murch. Phys. Rev. Lett. 121, 030604 (Vol. 121, Iss. 3 — 20 July 2018) DOI:https://doi.org/10.1103/PhysRevLett.121.030604 Published 17 July 2018

© 2018 American Physical Society

This paper is behind a paywall.

Nanotechnology Molecular Tagging for sniffing out explosives

A nifty technology for sniffing out explosives is described in a June 22, 2016 news item in Government Security News magazine. I do think they might have eased up on the Egypt Air disaster reference and the implication that it might have been avoided with the use of this technology,

The crash of an Egypt Air Flight 804 recently again raised concerns over whether a vulnerability in pre-flight security has led to another deadly terrorist attacks. Officials haven’t found a cause for the crash yet, but news reports indicate that officials believe either a bomb or fire are what brought the plane down [link included from press release].

Regardless of the cause, the Chief Executive Officer of British-based Ancon Technologies said that the incident shows the compelling need for more versatile and affordable explosive detection technology.

“There are still too many vulnerabilities in transportation systems around the world,” said CEO Dr. Robert Muir. “That’s why our focus has been on developing explosive detection technology that is highly efficient, easily deployable and economically priced.”

A June 21, 2015 Ancon Technologies press release on PR Web, which originated the news item, describes the technology in a little more detail,

Using nanotechnology to scan sensitive vapour readings, Ancon Technologies has developed unique security devices with exception sensitivity to detect explosive chemicals and materials. Called Nanotechnology Molecular Tagging, the technology is used to look for specific molecular markers that are emitted from the chemicals used in explosive compounds. An NMT device can then be programmed to look for these compounds and gauge concentrations.

“The result is unprecedented sensitivity for a device that is portable and versatile,” Dr. Muir said. “The technology is also highly selective, meaning it can distinguish the molecules is testing for against the backdrop of other chemicals and readings in the air.”

If terrorism is responsible for the crash of the Egypt Air flight on route to Cairo from Paris’ Charles de Gaulle Airport, the incident further shows the need for heightened screening processes, Muir said. Concerns about air travel’s vulnerabilities to terrorism were further raised in October when a Russian plane flying out of Egypt crashed in what several officials believe was a terrorist bombing.

Both cases show the need for improved security measures in airports around the world, especially those related to early explosive detection, Muir said. CNN reported that the Egypt Air crash would likely generate even more attention to airport security while Egypt has already been investing in new security measures following the October attack.

“An NMT device can bring laboratory-level sensitivity to the airport screening procedure, adding another level of safety in places where it’s needed most,” Muir said. “By being able to detect a compound at concentrations as small as a single molecule, NMT can pinpoint a threat and provide security teams with the early warning they need.”

The NMT device’s sensitivity and accuracy can also help balance another concern with airport security: long waits. Already, the Transportation Security Agency is coming under fire this summer for extended airport security screening lines, reports USA Today.

“An NMT device can produce results from test samples in minutes, meaning screenings can proceed at a reasonable pace without jeopardizing security,” Muir said.

Ancon Technologies has working arrangements with military and security agencies in both the United Kingdom and the United States, Muir said, following a recent round of investments. The company is headquartered in Canterbury, Kent and has an office in the U.S. in Bloomington, Minnesota.

So this is a sensing device and I believe this particular type can also be described as an artificial nose.

Welcome to Something About Science; another Canadian science blog

Lynn K, the Something About Science blogger is a (from the online profile),

…  Ph.D. candidate in biochemistry at the University of British Columbia. Biochemistry is the chemistry of life. I am interested in things that happen inside our bodies, such as what happens when you drink alcohol, what does it mean to have mutations, and how can we treat diseases like cancer and heart failure. Through this blog, I hope to intrigue your curiosity by sharing some bits of facts and stories about science in everyday life!

Lynn posts once a week on a variety of topics,

Top Posts

I have a personal fondness for the July 11, 2012 posting, What is a flame? — When a house catches fire…,

“FIRE!!” In the middle of the night last week, I was woken up to find a neighbor’s house fast ablaze. The entire framework crackled and was engulfed by flames which glared bright orange against the night. Fortunately, no one was hurt, as the house was under construction, and the neighboring houses had been evacuated before they, too, caught fire.

Here are some images that recapitulate the (hopefully) once-in-a-lifetime experience.

But this being a science blog, my question to you is, “What is a flame?” And better yet, can you explain flames in a way everyone, including children, can understand and enjoy learning?

Alan Alda and the Center for Communicating Science at Stony Brook University, New York, have asked the same question to scientists. The Flame Challenge invited scientists to communicate science clearly to the public by explaining what flames are in a way simple and fun, yet educational. The challenge received over 800 entries, which were judged by over 6,000 children aged 11.

Lynn goes on to announce the winner, Ben Ames, a PhD student in Austria and includes the challenge-winning video animation. You can watch the video and find out where you can post a question for next year’s challenge in Lynn’s What is a flame? posting.

Cotton and nanotechnology at the US Dept. of Agriculture

The April 2012 item by Jan Suszkiw of the US Dept. of Agriculture (on the Western Farm Press website) seemed strangely familiar as it focused on research into flame-retardant cotton. From the Suszkiw article,

In one ongoing project, the researchers have teamed with Texas A&M University scientists to evaluate a first-of-its-kind, environmentally friendly flame-retardant for cotton apparel and durable goods. Halogenated flame retardants have been among the most widely used chemical treatments, but there’s been a push to find alternatives that are more benign and that won’t cause treated fabric to stiffen, according to Condon [Brian Condon, Agricultural Research Service [ARS]).

I mentioned the research work in the context of a 2011 meeting of the American Chemical Society in my Sept. 6, 2011 posting (scroll down about 3/4 of the way) except the focus was on the Texas A&M University in College Station research team who had yet to collaborate with Condon’s team at the ARS,

In responding to the need for more environmentally friendly flame retardants, Grunlan’s [Jaime C. Grunlan] team turned to a technology termed “intumescence,” long used to fireproof exposed interior steel beams in buildings. At the first lick of a flame, an intumescent coating swells up and expands like beer foam, forming tiny bubbles in a protective barrier that insulates and shields the material below. The researchers are at Texas A&M University in College Station. …

Since the meeting last fall, the two teams (US ARS [Condon] and Texas A&M [Grunlan]) have collaborated to make cotton more flame retardant according to the April 2012 news article (Cotton Gets Nanotech and Biotech Treatment in New Orleans) on the US Dept. of Agriculture, Agricultural Research Service website (Note: I have removed a link),

Condon and CCUR (Cotton Chemistry and Utilization Research Unit) chemist SeChin Chang are collaborating with Texas A&M University (TAMU) scientists to evaluate a first-of-its-kind, environmentally friendly flame retardant for cotton apparel and durable goods.

Halogenated flame retardants have been among the most widely used chemical treatments for cotton. But there’s been a push to find alternatives that are not only more benign, but that also avoid imparting the same stiffness to fabric characteristic of some chemical treatments. For these and other reasons, “the textiles industry would like to move away from using halogenated flame retardants,” says Condon.

Made of water-soluble polymers, nanoscale clay particles, and other “green” ingredients, the ARS-TAMU flame retardant is applied as a nanocoating that reacts to open flame by rapidly forming a swollen, charred surface layer. This process, known as “intumescence,” stops the flame from reaching underlying or adjacent fibers.

A team led by Jaime Grunlan at TAMU’s Department of Mechanical Engineering, in College Station, Texas, originally developed the intumescent nanocoating using a layer-by-layer assembly. In this procedure, alternating layers of positively and negatively charged ingredients, including clay particles 50-100 nanometers wide, are deposited onto the surface of a desired material. The result is a striated nanocoating that, when viewed under a scanning electron or other high-powered microscope, resembles the stacked layers of a brick wall.

Condon’s interest was piqued after listening to Grunlan discuss his team’s research at a recent American Chemical Society meeting, and he approached the TAMU professor about potential benefits to cotton. That conversation, in turn, led to a cooperative research project enabling Condon and Chang to evaluate the nanocoating at CCUR.

Treating cotton for flame resistance isn’t a recent concept, adds Condon, whose lab is part of the ARS Southern Regional Research Center in New Orleans. In fact, some of the most successful early treatments were born of research conducted by Benerito [Ruth Benerito] and colleagues there several decades ago. (See “Cross-Linking Cotton,” Agricultural Research, February 2009, pp. 10-11.) Condon coauthored a 2011 ACS Nano paper on the potential of intumescent coatings together with Chang, Grunlan and his TAMU team, and Alexander Morgan of the University of Dayton Research Institute in Ohio.

Early trials of the nanocoating using standard flame-resistance tests are promising. In one case, 95 percent of treated cotton fabric remained intact after exposure to flame, whereas the untreated fabric used for comparison was completely destroyed

“What we’re investigating now is how well it will perform after repeated launderings of treated fabric,” says Condon. “After all, the coating contains clay, and that’s something detergents are made to remove.”

Even if the coating does eventually wash out and the treated fabric loses its flame resistance, the nanotech approach could still be used to protect textiles and durable goods that aren’t frequently washed, such as upholstery, mattress pads, box spring covers, automotive interiors, and firefighter coats.

This is one of the images that accompany the article,

Cross-section of a cotton fiber with clay nanoparticles attached. (from: http://www.ars.usda.gov/is/AR/archive/apr12/cotton0412.htm)

If you are interested in the work being done by the US Dept. of Agriculture’s Agricultural Research Service on cotton, there’s a lot more than I managed to excerpt.