Fast Spinning droplets form Superfluid Helium vortices

superfluid helium vortices

Artists rendition of quantum tornadoes

Physics, especially quantum physics is deliciously weird. Before writing about any news items involving it you have to wrap your head once, twice or a couple of times around what they are trying to do. In a recent news item scientists report that they have spotted densely packed tiny tornadoes nano sized droplets of liquid helium.

A superfluid is a fluid without any viscosity, resistance to flow, and happens to liquid helium when it gets really close to absolute zero. When a fluid reaches this state it defies the laws of regular physics and instead enter the weird reality of quantum physics. When helium forms a superfluid at -269C it can flow so easily it can form a never ending fountain and even counteract gravity. There is a video on youtube documenting this phenomenon, check it out.

Superfluid Helium Vortices aka. Tiny Tornadoes

The physicists knew about quantum vortices before they conducted this experiment. They had been seen earlier in super fluid helium, the surprise was how dense the vortices were and how fast they were spinning.
In the experiment Dr Daniel Rolles of the Deutsches Elektronen-Synchrotron shot streams of helium into a vacuum through a fine nozzle which was cooled to around -270 C.The nozzle formed extremely fine drops just 0.2-2 micrometers across. After being expelled through the nozzle the droplets reached super fluidity as a result of evaporation.
To observe the tiny spinning tornadoes the physicists used the first X-ray free-electron laser. The laser shoots incredibly rapid bursts of laser, each burst lasting only 1 ten trillionths of a second. The burst of light diffracted off the tiny helium droplets to reveal the pattern there within. But since the tornadoes at that point were invisible to the detector, to observe them the scientists had to add xenon atoms to the helium droplets which were drawn into the vortices. The images from the diffracted light revealed tornadoes that redefine miniscule, the diameter of the vortices were about that of a single atom. Too add even more weirdness  the helium drops spun at rotational speeds of up to 14MHZ, that’s 14 million rotations per second. This would rip apart any droplets of liquid in an instant, but not a superfluid. The helium droplets instead formed the quantum vortices.

What is the point?

The physicists believe that by studying these quantum vortices they can achieve a better understanding of how materials behaved in the very early stages of the universe. This could help them better understand the origins of the universe. Either way shooting mini droplets of helium into a vaccum and observing the results with a super fast laser is cool in a lot of different ways.