Imaging device captures vortices in quantum liquids for first time

Vortices that form in stirred fluids or tornadoes and cyclones are unpredictable, unlike in quantum liquids where vortices always have the same size due to quantum effects that arise at very cold temperatures, such as with the superfluid liquid helium-3.

Quantum vortices, however, are too small to be captured without tracer particles by a conventional camera.

Now, physicists led by Dr Theo Noble at Lancaster University have developed a new type of camera which uses particle-like disturbances to take images of collections of vortices instead of light.

Their work is published in Physical Review B.

The camera is a five-by-five array of pixels. Each of the 25 pixels is a millimetre-sized cylindrical cavity with a quartz tuning fork in the middle.

The team tested the camera on vortices created by a vibrating wire in a form of ultracold helium.

In a statement, Dr Theo Noble said: “The experiment works like shining a torch on a shadow puppet. We then measure the shadows cast by quantum vortices across the camera.”

Even with its low number of pixels, the new camera uncovered that most vortices form above the vibrating wire instead of developing all around it.

Dr Viktor Tsepelin, head of the Ultra Low Temperature Laboratory at Lancaster University, said that this was not predicted by mathematical theories or numerical simulations.

Dr Tsepelin’s goal now is to build a 90-pixel camera with a high enough resolution to image the details of development and decay of carefully prepared collections of vortices. This ability to observe the dynamics of superfluid helium-3 will improve the understanding of the turbulent motion of quantum fluids and turbulence in general.

Dr Viktor Tsepelin said: “It is exciting to see that our prototype is working. The high-resolution camera could also be used to image other topological defects existing in superfluid helium-3 allowing us to have a glimpse at an analogue of the Early Universe.”