Tag Archives: superfluids

‘Superconductivity: The Musical!’ wins the 2018 Dance Your Ph.D. competition

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I can’t believe that October 24, 2011 was the last time the Dance Your Ph.D. competition was featured here. Time flies, eh? Here’s the 2018 contest winner’s submission, Superconductivity: The Musical!, (Note: This video is over 11 mins. long),

A February 17, 2019 CBC (Canadian Broadcasting Corporation) news item introduces the video’s writer, producer,s musician, and scientist,

Swing dancing. Songwriting. And theoretical condensed matter physics.

It’s a unique person who can master all three, but a University of Alberta PhD student has done all that and taken it one step further by making a rollicking music video about his academic pursuits — and winning an international competition for his efforts.

Pramodh Senarath Yapa is the winner of the 2018 Dance Your PhD contest, which challenges scientists around the world to explain their research through a jargon-free medium: dance.

The prize is $1,000 and “immortal geek fame.”

Yapa’s video features his friends twirling, swinging and touch-stepping their way through an explanation of his graduate research, called “Non-Local Electrodynamics of Superconducting Wires: Implications for Flux Noise and Inductance.”

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Jennifer Ouelette’s February 17, 2019 posting for the ars Technica blog offers more detail (Note: A link has been removed),

Yapa’s research deals with how matter behaves when it’s cooled to very low temperatures, when quantum effects kick in—such as certain metals becoming superconductive, or capable of conducting electricity with zero resistance. That’s useful for any number of practical applications. D-Wave Systems [a company located in metro Vancouver {Canada}], for example, is building quantum computers using loops of superconducting wire. For his thesis, “I had to use the theory of superconductivity to figure out how to build a better quantum computer,” said Yapa.

Condensed matter theory (the precise description of Yapa’s field of research) is a notoriously tricky subfield to make palatable for a non-expert audience. “There isn’t one unifying theory or a single tool that we use,” he said. “Condensed matter theorists study a million different things using a million different techniques.”

His conceptual breakthrough came about when he realized electrons were a bit like “unsociable people” who find joy when they pair up with other electrons. “You can imagine electrons as a free gas, which means they don’t interact with each other,” he said. “The theory of superconductivity says they actually form pairs when cooled below a certain temperature. That was the ‘Eureka!’ moment, when I realized I could totally use swing dancing.”

John Bohannon’s Feb. 15, 2019 article for Science (magazine) offers an update on Yapa’s research interests (it seems that Yapa was dancing his Masters degree) and more information about the contest itself ,

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“I remember hearing about Dance Your Ph.D. many years ago and being amazed at all the entries,” Yapa says. “This is definitely a longtime dream come true.” His research, meanwhile, has evolved from superconductivity—which he pursued at the University of Victoria in Canada, where he completed a master’s degree—to the physics of superfluids, the focus of his Ph.D. research at the University of Alberta.

This is the 11th year of Dance Your Ph.D. hosted by Science and AAAS. The contest challenges scientists around the world to explain their research through the most jargon-free medium available: interpretive dance.

“Most people would not normally think of interpretive dance as a tool for scientific communication,” says artist Alexa Meade, one of the judges of the contest. “However, the body can express conceptual thoughts through movement in ways that words and data tables cannot. The results are both artfully poetic and scientifically profound.”

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Getting back to the February 17, 2019 CBC news item,

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Yapa describes his video, filmed in Victoria where he earned his master’s degree, as a “three act, mini-musical.”

“I envisioned it as talking about the social lives of electrons,” he said. “The electrons starts out in a normal metal, at normal temperatures….We say these electrons are non-interacting. They don’t talk to each other. Electrons ignore each other and are very unsociable.”

The electrons — represented by dancers wearing saddle oxfords, poodle skirts, vests and suspenders — shuffle up the dance floor by themselves.

In the second act, the metal is cooled.

“The electrons become very unhappy about being alone. They want to find a partner, some companionship for the cold times,” he said

That’s when the electrons join up into something called Cooper pairs.

The dancers join together, moving to lyrics like, “If we peek/the Coopers are cheek-to-cheek.

In the final act, Yapa gets his dancers to demonstrate what happens when the Cooper pairs meet the impurities of the materials they’re moving in. All of a sudden, a group of black-leather-clad thugs move onto the dance floor.

“The Cooper pairs come dancing near these impurities and they’re like these crotchety old people yelling and shaking their fists at these young dancers,” Yapa explained.

Yapa’s entry to the annual contest swept past 49 other contestants to earn him the win. The competition is sponsored by Science magazine and the American Association for the Advancement of Science.

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Congratulations to Pramodh Senarath Yapa.

McGill University researchers put the squeeze Tomonaga-Luttinger theory in quantum mechanics

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McGill University (Montréal, Québec, Canada) researchers testing the Tomonaga-Luttinger theory had international help according to a May 15, 2015 news item on ScienceDaily,

We all know intuitively that normal liquids flow more quickly as the channel containing them tightens. Think of a river flowing through narrow rapids.

But what if a pipe were so amazingly tiny that only a few atoms of superfluid helium could squeeze through its opening at once? According to a longstanding quantum-mechanics model, the superfluid helium would behave differently from a normal liquid: far from speeding up, it would actually slow down.

For more than 70 years, scientists have been studying the flow of helium through ever smaller pipes. But only recently has nanotechnology made it possible to reach the scale required to test the theoretical model, known as the Tomonaga-Luttinger theory (after the scientists who developed it).

Now, a team of McGill University researchers, with collaborators at the University of Vermont and at Leipzig University in Germany, has succeeded in conducting experiments with the smallest channel yet – less than 30 atoms wide. In results published online today in Science Advances, the researchers report that the flow of superfluid helium through this miniature faucet does, indeed, appear to slow down.

A May 15, 2015 University of McGill news release (also on EurekAlert), which originated the news item, expands on the theme and notes this is one step on the road to proving the theory,

“Our results suggest that a quantum faucet does show a fundamentally different behaviour,” says McGill physics professor Guillaume Gervais, who led the project. “We don’t have the smoking gun yet. But we think this a great step toward proving experimentally the Tomonaga-Luttinger theory in a real liquid.”

The zone where physics changes

Insights from the research could someday contribute to novel technologies, such as nano-sensors with applications in GPS systems. But for now, Gervais says, the results are significant simply because “we’re pushing the limit of understanding things on the nanoscale. We’re approaching the grey zone where all physics changes.”

Prof. Adrian Del Maestro from the University of Vermont has been employing high-performance computer simulations to understand just how small the faucet has to be before this new physics emerges. “The ability to study a quantum liquid at such diminutive length scales in the laboratory is extremely exciting as it allows us to extend our fundamental understanding of how atoms cooperate to form the superfluid state of matter,” he says. “The superfluid slowdown we observe signals that this cooperation is starting to break down as the width of the pipe narrows to the nanoscale” and edges closer to the exotic one-dimensional limit envisioned in the Tomonaga-Luttinger theory.

Building what is probably the world’s smallest faucet has been no simple task. Gervais hatched the idea during a five-minute conversation over coffee with a world-leading theoretical physicist. That was eight years ago. But getting the nano-plumbing to work took “at least 100 trials – maybe 200,” says Gervais, who is a fellow of the Canadian Institute for Advanced Research.

A beam of electrons as drill bit

Using a beam of electrons as a kind of drill bit, the team made holes as small as seven nanometers wide in a piece of silicon nitride, a tough material used in applications such as automotive diesel engines and high-performance ball bearings. By cooling the apparatus to very low temperatures, placing superfluid helium on one side of the pore and applying a vacuum to the other, the researchers were able to observe the flow of the superfluid through the channel. Varying the size of the channel, they found that the maximum speed of the flow slowed as the radius of the pore decreased.

The experiments take advantage of a unique characteristic of superfluids. Unlike ordinary liquids – water or maple syrup, for example – superfluids can flow without any viscosity. As a result, they can course through extremely narrow channels; and once in motion, they don’t need any pressure to keep going. Helium is the only element in nature known to become a superfluid; it does so when cooled to an extremely low temperature.

An inadvertent breakthrough

For years, however, the researchers were frustrated by a technical glitch: the tiny pore in the silicon nitride material kept getting clogged by contaminants. Then one day, while Gervais was away at a conference abroad, a new student in his lab inadvertently deviated from the team’s operating procedure and left a valve open in the apparatus. “It turned out that this open valve kept the hole open,” Gervais says. “It was the key to getting the experiment to work. Scientific breakthroughs don’t always happen by design!”

Prof. Bernd Rosenow, a quantum physicist at Leipzig University’s Institute for Theoretical Physics, also contributed to the study.

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

Critical flow and dissipation in a quasi–one-dimensional superfluid by Pierre-François Duc, Michel Savard, Matei Petrescu, Bernd Rosenow, Adrian Del Maestro, Guillaume Gervais. Science Advances 15 May 2015: Vol. 1 no. 4 e1400222 DOI: 10.1126/sciadv.1400222

This is an open access paper.