superfluid helium

3

Superfluid Helium

It was previously thought that superfluid Helium would flow continuously without losing kinetic energy. Mathematicians at Newcastle University demonstrated that this is only the case on a surface completely smooth down to the scale of nanometers; and no surface is that smooth.

When a regular fluid like water is passing over a surface, friction creates a boundary layer that ‘sticks’ to surfaces. Just like a regular fluid, when superfluid Helium passes over a rough surface there is a boundary layer created. However the cause is very different. As superfluid Helium flows past a rough surface, mini tornados are created which tangle up and stick together creating a slow-moving boundary layer between the free-moving fluid and the surface. This lack of viscosity is one of the key features that define what a superfluid is and now we know why it still loses kinetic energy when passing over a rough surface.

Now we can use this information to help our efforts on applications of superfluids in precision measurement devices such as gyroscopes (I think this was on the Big Bang theory where they make a gyroscope using superfluid Helium that can maintain angular momentum indefinitely because it would flow across a smooth surface without losing kinetic energy) and as coolants.

youtube

Solid, liquid, gas and… Superfluid?

One moment it’s trapped in a container like water, then it’s flowing uphill, or escaping through tiny pores it couldn’t previously navigate.

Strange things happen when you cool Helium to within a few degrees of absolute zero - it loses all viscosity and literally no longer experiences friction.

This video is two mind-bending minutes on a truly cool state of matter - superfluidity.

[Steve and Tony are discussing their day over dinner]

Steve: So, tell me about your day– how’s it going with the particle detector?

Tony: Wow! You remember that?

Steve: Yeah, I listen to what you say. You’re building a particle detector using superfluid helium.

Tony: You know, when you talk like that, I want to take you right here on this table.

Steve: And you know from past experience this table cannot support both our weight.

3

‘Perfect liquid’ quark-gluon plasma is the most vortical fluid

Particle collisions recreating the quark-gluon plasma (QGP) that filled the early universe reveal that droplets of this primordial soup swirl far faster than any other fluid.

The new analysis of data from the Relativistic Heavy Ion Collider (RHIC) - a U.S. Department of Energy Office of Science User Facility for nuclear physics research at Brookhaven National Laboratory - shows that the “vorticity” of the QGP surpasses the whirling fluid dynamics of super-cell tornado cores and Jupiter’s Great Red Spot by many orders of magnitude, and even beats out the fastest spin record held by nanodroplets of superfluid helium.

The results, just published in Nature, add a new record to the list of remarkable properties ascribed to the quark-gluon plasma. This soup made of matter’s fundamental building blocks - quarks and gluons - has a temperature hundreds of thousands of times hotter than the center of the sun and an ultralow viscosity, or resistance to flow, leading physicists to describe it as “nearly perfect.”

By studying these properties and the factors that control them, scientists hope to unlock the secrets of the strongest and most poorly understood force in nature - the one responsible for binding quarks and gluons into the protons and neutrons that form most of the visible matter in the universe today.

Specifically, the results on vorticity, or swirling fluid motion, will help scientists sort among different theoretical descriptions of the plasma. And with more data, it may give them a way to measure the strength of the plasma’s magnetic field - an essential variable for exploring other interesting physics phenomena.

“Up until now, the big story in characterizing the QGP is that it’s a hot fluid that expands explosively and flows easily,” said Michael Lisa, a physicist from Ohio State University (OSU) and a member of RHIC’s STAR collaboration. “But we want to understand this fluid at a much finer level. Does it thermalize, or reach equilibrium, quickly enough to form vortices in the fluid itself? And if so, how does the fluid respond to the extreme vorticity?” The new analysis, which was led by Lisa and OSU graduate student Isaac Upsal, gives STAR a way to get at those finer details.

Aligning spins

“The theory is that if I have a fluid with vorticity - a whirling substructure - it tends to align the spins of the particles it emits in the same direction as the whirls,” Lisa said. And, while there can be many small whirlpools within the QGP all pointing in random directions, on average their spins should align with what’s known as the angular momentum of the system - a rotation of the system generated by the colliding particles as they speed past one another at nearly the speed of light.

To track the spinning particles and the angular momentum, STAR physicists correlated simultaneous measurements at two different detector components. The first, known as the Beam-Beam Counters, sit at the front and rear ends of the house-size STAR detector, catching subtle deflections in the paths of colliding particles as they pass by one another. The size and direction of the deflection tells the physicists how much angular momentum there is and which way it is pointing for each collision event.

Meanwhile, STAR’s Time Project Chamber, a gas-filled chamber that surrounds the collision zone, tracks the paths of hundreds or even thousands of particles that come out perpendicular to the center of the collisions.

“We’re specifically looking for signs of Lambda hyperons, spinning particles that decay into a proton and a pion that we measure in the Time Projection Chamber,” said Ernst Sichtermann, a deputy STAR spokesperson and senior scientist at DOE’s Lawrence Berkeley National Laboratory. Because the proton comes out nearly aligned with the hyperon’s spin direction, tracking where these “daughter” protons strike the detector can be a stand-in for tracking how the hyperons’ spins are aligned.

“We are looking for some systematic preference for the direction of these daughter protons aligned with the angular momentum we measure in the Beam-Beam Counters,” Upsal said. “The magnitude of that preference tells us the degree of vorticity - the average rate of swirling - of the QGP.”

Super spin

The results reveal that RHIC collisions create the most vortical fluid ever, a QGP spinning faster than a speeding tornado, more powerful than the fastest spinning fluid on record. “So the most ideal fluid with the smallest viscosity also has the most vorticity,” Lisa said.

This kind of makes sense, because low viscosity in the QGP allows the vorticity to persist, Lisa said. “Viscosity destroys whirls. With QGP, if you set it spinning, it tends to keep on spinning.”

The data are also in the ballpark of what different theories predicted for QGP vorticity. “Different theories predict different amounts, depending on what parameters they include, so our results will help us sort through those theories and determine which factors are most relevant,” said Sergei Voloshin, a STAR collaborator from Wayne State University. “But most of the theoretical predications were too low,” he added. “Our measurements show that the QGP is even more vortical than predicted.”

This discovery was made during the Beam Energy Scan program, which exploits RHIC’s unique ability to systematically vary the energy of collisions over a range in which other particularly interesting phenomena have been observed. In fact, theories suggest that this may be the optimal range for the discovery and subsequent study of the vorticity-induced spin alignment, since the effect is expected to diminish at higher energy.

Increasing the numbers of Lambda hyperons tracked in future collisions at RHIC will improve the STAR scientists’ ability to use these measurements to calculate the strength of the magnetic field generated in RHIC collisions. The strength of magnetism influences the movement of charged particles as they are created and emerge from RHIC collisions, so measuring its strength is important to fully characterize the QGP, including how it separates differently charged particles.

“Theory predicts that the magnetic field created in heavy ion experiments is much higher than any other magnetic field in the universe,” Lisa said. At the very least, being able to measure it accurately may nab another record for QGP.


TOP IMAGE….Tracking particle spins reveals that the quark-gluon plasma created at the Relativistic Heavy Ion Collider is more swirly than the cores of super-cell tornados, Jupiter’s Great Red Spot, or any other fluid! Credit Brookhaven National Laboratory

CENTRE IMAGE….Telltale signs of a lambda hyperon (Λ) decaying into a proton (p) and a pion (π-) as tracked by the Time Projection Chamber of the STAR detector. Because the proton comes out nearly aligned with the hyperon’s spin direction, tracking where these 'daughter’ protons strike the detector can be a stand-in for tracking how the hyperons’ spins are aligned. Credit Brookhaven National Laboratory

LOWER IMAGE….The STAR detector at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory with a superimposed image of particles tracked by the detector. Credit Brookhaven National Laboratory

Superfluidity & Liquid Helium

Author: longestpathsearch​ in collaboration with rudescience​ (first in a series of collaborative posts between rudescience and I).

What is a Superfluid?

If you’ve ever looked at the first gif… You may find it a bit odd. What exactly is going on there? Why are these random droplets so interesting? Well, that’s because it’s not that the fluid is somehow getting through the little membrane. It’s actually crawling around the walls of the container over and out of it, and collecting at the bottom! This happens because one of the properties of superfluids is that it has zero viscosity; it essentially has the ability to crawl over itself without any kind of friction, which gives all sorts of weird results like above. 

Why do Superfluids Happen?

So why exactly are superfluids a thing? Why don’t all fluids behave like superfluids? What makes something a superfluid? [1]

At first, it might come as a surprise that Helium-4 never has a solid state. No matter how low you make the temperature, you will never be able to get crystal He-4 at even slightly reasonable pressures.[2] This happens for two main reasons, each of which rule out majority of other elements as candidates for superfluids:

  1. The average inter-atomic distances (the space between atoms) of He-4 at those temperatures is almost 10x larger than the deBroglie wavelength of those atoms (essentially, how large each atom is, quantum mechanically). This means that the fluid is now in the realm of quantum mechanics, and therefore thinking of the fluid as a collection of mostly-independent particles will do little more than lead us down a garden path.
  2. The zero-point energy of He-4 at those temperatures causes it to essentially vibrate too rapidly to ever solidify into a crystal lattice; this effect is mostly due to the low atomic mass of Helium vs that of other similar elements.

Combining all of these properties is what puts He-4 as a prime candidate for a superfluid.

Why Are Superfluids Weird?

I mean, apart from the fact that Quantum Mechanics is weird? So, if the fact that He-4 isn’t solid at any temperature and non-extreme pressures doesn’t surprise you, I guess there’s also the notion that it seems to almost completely disregard Newtonian physics—just because it can, apparently. Anyways, putting together idea that since the fluid itself is strongly-interacting and a bit more of quantum mechanics[3] we receive this notion that the wavefunction that describes a slice of the fluid is essentially rigid. In fact, not only that, but it also tells us that such a slice of the fluid is one big quantum state with many bodies[4]. Since this ensemble carries zero entropy, we cannot lose any energy to heat! Which means that there is no friction within the liquid itself.  Well, that’s enough of the word ‘super’ for the next year and a half (superfluids, superflows, etc, etc), but for more references, check outSuperconductivity, Superfluids, and Condensates by Annett. Overall, it’s a decent intro to Condensed-Matter which can be read after a second course in QM and an introduction to statistical mechanics.

Footnotes

[1] Though it’s possible to get into the nitty-gritty of particle spins (which may be a post for later) and why Helium-4 (spin-0) is superfluid with certain properties vs. Helium-3 (with spin-½), I won’t make a case for this because He-3 is complicated to treat without referring to a decent amount of QM and explaining Cooper Pairs. 
[2] Of course, squish it down enough (2.5 Million Pascals) and you’ll surely come out with a He-4 crystal at 0 Kelvin. 
[3] By this, I mean Time-Dependent perturbation theory. The rough argument goes: take the capillary roughness (the atomic-level imperfections) as perturbations to the ensemble from the ensemble’s rest frame and then apply Fermi’s Golden rule. By considering each case, we get 3 distinct modes of behavior for a given momentum, (1) a phonon mode, where the fluid is essentially a solid clump of moving mass, (2) a roton mode, where, if we’re looking at a single particle from its frame of reference, all of the particles appear to rotate around it in a weird backflow way, and (3) a typical mode where it approximates a normal liquid; this discovery is thanks to Landau. 
[4] To be a bit more accurate, there are two probability flows induced, one is a normal-flow which has non-zero entropy and behaves essentially like a typical liquid with independent, weakly-interacting particles, and a superflow which behaves purely like a superfluid or as part of a condensate—a large system of bosons all in the same state.

together-shamy  asked:

OMG! I love Dave too! Can u write some more about him? Please and thank you! 😊

Ten minutes late was fashionable, fifteen was worrisome, 20 was rude, and at an hour it was clear he had been stood up again. Dave looks at his watch and sighs yet another lonely Saturday night. He signals to the waitress to bring him his check.

“Giving up on her coming?” The waitress asks kindly.

“Well I suppose one can assume that after an hour of patiently waiting your date is not arriving. I’m not surprised though. My wife left me for a french chef. The only good date I have been on in four years ended with her snogging the brains out of her ex boyfriend while I cheered them on.”

“Oh no!” The waitress says shocked. “That must of been awful for you.”

“No, it was alright. Her boyfriend was a bit of an idol of mine, so at least I can say I met him now. Got to shake his hand and everything! Well before he grabbed my girl and kissed her like there was no tomorrow. But I told him too, so it’s alright.”

“Tell you what, your glass of wine is on me. You have at a pretty rough go of it. What was he like an actor or musician or something?” She asks curiously.

“Physicist actually, the world renowned Dr.Sheldon Cooper.”

“That name sounds familiar…” she says tapping her pen on the table

“Are you a big science buff as well?” He asks excited but she shakes her head no.

“Not at all… Oh I know why! I think that guy called here for a reservation and had all these crazy demands he wanted met.”

“From what Amy told me that sounds like him.”

“He is over there.” She says pointing to a table in the distance. “Is that him?”

“Oh god! It is them.” He says covering his face with his hands. Misreading his excitement for dread the waitress puts her and on his shoulder to console him.

“You want me to help you…” But before she can finish her sentence Dave is up and heading over to the table. Amy looks lovely as always dressed in a purple dress and cardigan. Sheldon looks a bit more formal than he last saw him wearing a dove gray suit.

“Fancy meeting you two here!” He says approaching the table. “Don’t you two clean up nice.” He says placing both his hands on the table and looking at them excited. Amy gives him a tight smile and Sheldon nods his head at him.

“Hello.” He says stiffly

“Hi Dave, what brings you here?” She asks raising her eyebrows.

“I’m not stalking him if that is what you are worried about.” He jokes but Amy looks at him skeptically. “I was here for a date, but it appears I have been stood up.”

“I am so sorry.” Amy tells him gently.

“It’s par for the course really…I was just heading out.”

“Too bad, if you weren’t leaving I would have invited you to join our table. Well off you go.” Sheldon says sarcastically.

“Really? Oh that is so kind of you. I did not even get to eat yet I was going to pick up a frozen meal on my way home.” Dave says grabbing a chair and pulling it up to the table meant for only two.

“I think this table was just meant for two.” Amy tells him pointedly.

“There is plenty of room!” Dave says setting his elbows up on the table to demonstrate the space then he sets his chin in his hands and stares dreamily at Sheldon. “So tell me Dr. Cooper how did you come up with the idea for superfluid helium?”

“Actually it was Leonard who came up with idea.” Amy says grumpily and Sheldon cuts his eyes at her.

“Dr. Leonard Hofstadter! I got to meet him too! Remember Amy? when that little blonde girl backed into my car.”

“Leonard may have had the initial idea but I am the one who worked out all the math. Without me it would still just me a twinkle behind Leonard’s dull eyes.” Sheldon points out.

“That is amazing, tell me how long did it take you to work out the math and write out the paper once you had the idea?” Dave asks.

“I worked all night on it so maybe six hours give or take.” Sheldon tells him.

“Fascinating! How soon after you finished did you publish your findings?” Dave asks as a waiter comes over and takes their orders.

“That morning, I was sure my calculations were correct. There was no reason to wait and let someone else take our idea.”

“I wish I had your confidence. It would take me years to get the guts to publish something like that. Hell, it would take me a decade to work out the math alone. You say you were able to work it out all in one night?”`

“You know it is hard not to like you when you are so relentlessly flattering.” Sheldon tells him smiling.

“I am told I have a way of worming my way into your heart.” Dave says and with that Sheldon and Dave start talking about physics while Amy grows more and more annoyed.

“So what was your lowest moment in science if you don’t mind me asking? It seems like you have a career filled with highs.” Dave gushes.

“It is true I have not had many misses.” Sheldon starts.

“How about when you had to publish your retraction when you thought you had found an element? Or when you had to work together with Kripke on a paper and his research was ahead of yours?” Amy says growing little tired of the Sheldon praise party.

“Kripke? Isn’t that the bloke you told me sent you nude photos as an invitation to a date?” Dave asks Amy and she turns red and stammers.

“Yes but that is not really important.”

“Excuse me? Barry Kripke sent you nude photos?” Sheldon says shocked.

“Yes it’s not a big deal, he asked me out on a date and then sent me photos of him au naturel.” Amy says taking a bite of food to avoid talking more.

“I would say it is a big deal! I was under the assumption that I was the only man you had ever seen “au naturel” but apparently Kripke beat me to the punch.” Sheldon say annoyed.

“I have to go to the restroom.” Amy says getting up and storming off.

“I am so sorry, I did not mean to open up a sore spot there really. Amy was quite horrified about it. We were talking about terrible first dates. She told me she did not have many first dates. That most of her dates have ended before she even meet them. Then that is how it came up. If it makes you feel any better I am sure you are the only man she has any interest in actually seeing naked. It was made abundantly clear to me that all forms of physical contact where off the table.”

“That was one of first things she ever said to me. Before we took our relationship any further all forms of physical contact up to and including coitus where off the table. Flash forward five years and that has changed, nothing is off the table now. I know she did not hold that with you either I saw you kiss her.”

“I only kissed her the once outside her building. I kind of stole a peck against her wishes How did you see that?”

“I was across the street on my way to propose to her. Then I saw her kiss you and changed my mind. Much like tonight I had every intention of popping the question until you should up. “

“You are going to propose tonight. I feel like such a heel! I suppose that is why you are in a. fancy resteraunt dressed to the nines.”

“I was going to. This is the same restaurant we had our second anniversary meal. Amy almost stormed out on me but then I told her what she meant to me and I convinced her to stay. I was going to make a speech about that and then ask her if I could convince her to stay with me forever.”

“Oh she is going to love that isn’t she.” Dave says excited. “Do you have the ring? Let’s have a look at it!”

“I am not going to ask her now.” Sheldon tells him.

“Oh right, I guess I have kind of horned in on your evening haven’t I? I wouldn’t ask her now either better wait until the moment is right.”

“Yes you have.” He tells him rolling his eyes. “For your information this is my third failed attempt at proposing to Amy and failure is not something I am used too.”

“Third? I know about two times what was the other?”

“The night she broke up with me… I was planning on asking her then.” He says sad,y and Dave instantly regrets asking. It is obviously painful for him to think about.

“Well I won’t cut in on your romantic evening any longer. Let me just leave you my cut for dinner and I will be off.” Dave says getting up and tossing a fifty on the table. “As always Dr. Cooper it has been a pleasure. If you ever want to talk shop, or shoot the breeze, just give me a call. Amy should have my number. You know what? she may have deleted it after getting back with you. So perhaps I should write it down just in case you need me for anything. Or want me for anything! Amy told me you are a big Doctor Who fan. I come from the land he comes from. You know we could talk about that… “ he rambles but seeing the annoyed look Sheldon is giving him he stops in his tracks. “Or not.” He says weakly but he scribbles his number on a sheet of scrap paper in his pocket anyways and hands it too Sheldon then ambles off.Amy comes back to the table and is relieved to see that Dave is gone.

“I am sorry for running off, I just did not want to be around him any more.” Amy says sitting back down.

“Your ex-boyfriend certainly is enthusiastic.” He tells her and she puffs out her cheeks.

“Dave is not my ex-boyfriend! We went on four dates. One where he talked about you the entire time. Then another where… Well you were there.” She tells him smiling and he smiles back but then turns serious.

“Amy I have been meaning to ask you something.” He starts nervously.

“You can ask me anything.” Amy tells him equally as nervous, before Dave sat down she was sure tonight would be the night Sheldon asked her to marry him. Penny had told her about the rung and ever since they got back together she had been awaiting his popping the question.

“If the odds had not been stacked in my favor. If things had been different and Dave had not been a superfan of mine. Would things turned out differently? Would you still be here with me?”

“Why would you ask that?” Amy says shocked.

“Dave being here made me think of somethings. It is not lost on me how lucky I was that the man you met happened to be… Him.”

“Sheldon no matter who I would have met it wouldn’t have mattered because he is not you.” Amy tells him. As Sheldon pays the bill and they get up to leave.

“You go ahead and pull the car around.” Sheldon tells Amy and he hangs back to retrieve the engagement ring from the waiter who was supposed to slip it into dessert.

“Cold feet?” The waiter asks handing him back the ring.

“Not at all. I will ask her to marry me. Just not today” Sheldon tells him as he walks out of tbe restaurant.

This is going to be a couple different parts. Let me know if you want more.

youtube

Superfluids, a special type of fluid located below the lambda point near absolute zero, exhibit some mind-bending properties like zero viscosity and zero entropy. They are, in essence, a macroscopic manifestation of quantum mechanics. Here their thermomechanical, or fountain, effect is explained. This bizarre state of matter isn’t only found in laboratories, though. Scientists now think that superfluids may exist at the heart of neutron stars.

Researchers map quantum vortices inside superfluid helium nanodroplets

First ever snapshots of spinning nanodroplets reveal surprising features

Scientists have, for the first time, characterized so-called quantum vortices that swirl within tiny droplets of liquid helium. The research, led by scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), the University of Southern California, and SLAC National Accelerator Laboratory, confirms that helium nanodroplets are in fact the smallest possible superfluidic objects and opens new avenues to study quantum rotation.

“The observation of quantum vortices is one of the most clear and unique demonstrations of the quantum properties of these microscopic objects,” says Oliver Gessner, senior scientist in the Chemical Sciences Division at Berkeley Lab. Gessner and colleagues, Andrey Vilesov of the University of Southern California and Christoph Bostedt of SLAC National Accelerator Laboratory at Stanford, led the multi-facility and multi-university team that published the work this week in Science.

The finding could have implications for other liquid or gas systems that contain vortices, says USC’s Vilesov. “The quest for quantum vortices in superfluid droplets has stretched for decades,” he says. “But this is the first time they have been seen in superfluid droplets.”

Superfluid helium has long captured scientist’s imagination since its discovery in the 1930s. Unlike normal fluids, superfluids have no viscosity, a feature that leads to strange and sometimes unexpected properties such as crawling up the walls of containers or dripping through barriers that contained the liquid before it transitioned to a superfluid.

Helium superfluidity can be achieved when helium is cooled to near absolute zero (zero kelvin or about -460 degrees F). At this temperature, the atoms within the liquid no longer vibrate with heat energy and instead settle into a calm state in which all atoms act together in unison, as if they were a single particle.

For decades, researchers have known that when superfluid helium is rotated–in a little spinning bucket, say–the rotation produces quantum vortices, swirls that are regularly spaced throughout the liquid. But the question remained whether anyone could see this behavior in an isolated, nanoscale droplet. If the swirls were there, it would confirm that helium nanodroplets, which can range in size from tens of nanometers to microns, are indeed superfluid throughout and that the motion of the entire liquid drop is that of a single quantum object rather than a mixture of independent particles.

But measuring liquid flow in helium nanodroplets has proven to be a serious challenge. “The way these droplets are made is by passing helium through a tiny nozzle that is cryogenically cooled down to below 10 Kelvin,” says Gessner. “Then, the nanoscale droplets shoot through a vacuum chamber at almost 200 meters-per-second. They live once for a few milliseconds while traversing the experimental chamber and then they’re gone. How do you show that these objects, which are all different from one another, have quantum vortices inside?”

The researchers turned to a facility at SLAC called the Linac Coherent Light Source (LCLS), a DOE Office of Science user facility that is the world’s first x-ray free-electron laser. This laser produces very short light pulses, lasting just a ten-trillionth of a second, which contain a huge number of high-energy photons. These intense x-ray pulses can effectively take snapshots of single, ultra-fast, ultra-small objects and phenomena.

“With the new x-ray free electron laser, we can now image phenomenon and look at processes far beyond what we could imagine just a decade ago,” says Bostedt of SLAC. “Looking at the droplets gave us a beautiful glimpse into the quantum world. It really opens the door to fascinating sciences.”

In the experiment, the researchers blasted a stream of helium nanodroplets across the x-ray laser beam inside a vacuum chamber; a detector caught the pattern that formed when the x-ray light diffracted off the drops.

The diffraction patterns immediately revealed that the shape of many droplets were not spheres, as was previously assumed. Instead, they were oblate. Just as the Earth’s rotation causes it to bulge at the equator, so too do rotating nanodroplets expand around the middle and flatten at the top and bottom.

But the vortices themselves are invisible to x-ray diffraction, so the researchers used a trick of adding xenon atoms to the droplets. The xenon atoms get pulled into the vortices and cluster together.

“It’s similar to pulling the plug in a bathtub and watching the kids’ toys gather in the vortex,” says Gessner. The xenon atoms diffract x-ray light much stronger than the surrounding helium, making the regular arrays of vortices inside the droplet visible. In this way, the researchers confirmed that vortices in nanodroplets behave as those found in larger amounts of rotating superfluid helium.

Armed with this new information, the researchers were able to determine the rotational speed of the nanodroplets. They were surprised to find that the nanodroplets spin up to 100,000 times faster than any other superfluid helium sample ever studied in a laboratory.

Moreover, while normal liquid drops will change shape as they spin faster and faster–to resemble a peanut or multi-lobed globule, for instance–the researchers saw no evidence of such shapeshifting in the helium nanodroplets. “Essentially, we’re exploring a new regime of quantum rotation with this matter,” Gessner says.

“It’s a new kind of matter in a sense because it is a self-contained isolated superfluid,” he adds. “It’s just all by itself, held together by its own surface tension. It’s pretty perfect to study these system


IMAGE…This is an illustration of analysis of superfluid helium nanodroplets. Droplets are emitted via a cooled nozzle (upper right) and probed with x-ray from the free-electron laser. The multicolored pattern (upper left) represents a diffraction pattern that reveals the shape of a droplet and the presence of quantum vortices such as those represented in the turquoise circle with swirls (bottom center).

Credit: Felix P. Sturm and Daniel S. Slaughter, Berkeley Lab.