#superfluids

Ordinary matter, when cooled, transitions from a gas into a liquid. Cool it further still, and it freezes into a solid. Quantum matter, however, can behave very differently. In the early 20th century, researchers discovered that when helium is cooled, it transitions from a seemingly ordinary gas into a so-called superfluid. Superfluids flow without losing any energy, among other quantum quirks, like an ability to climb out of containers. What happens when you cool a superfluid down even more? The answer to this question has eluded physicists since they first started asking it half a century ago. Writing today in Nature, a team led by physicists Cory Dean from Columbia University and Jia Li from the University of Texas at Austin has observed a superfluid, which normally remains in constant motion, come to a standstill. "For the first time, we've seen a superfluid undergo a phase transition to become what appears to be a supersolid," said Dean. It's like water freezing to ice, but at the quantum level.

New optical centrifuge unlocks the secrets of frictionless superfluids

Physicists have developed a new way to control the rotation of molecules inside tiny droplets of liquid helium, marking an important advance in the study of superfluids. By using a specially designed optical centrifuge, the team was able to precisely spin molecules suspended in liquid helium nano-droplets, giving scientists a powerful new tool for exploring these unusual frictionless materials. The achievement represents the first successful demonstration of controlled molecular rotation inside a superfluid. Researchers can now directly adjust both the direction and speed of a molecule's rotation, making it possible to investigate how molecules interact with their quantum surroundings at different rotational frequencies. The work, led by researchers at the University of British Columbia (UBC) in collaboration with the University of Freiburg, was published in Physical Review Letters.

Scientists Confirm Mysterious 'Second Sound' Exists

Introduction to the Mysterious 'Second Sound'Discover what's happening now with Scientists Confirm Mysterious 'Second Sound' Exists. Wait till you hear this! For the first time, MIT scientists have successfully imaged how heat actually travels in a wave, known as a “second sound,” through this exotic fluid. This breakthrough discovery is leaving many in the scientific community mind-blown.What is the 'Second Sound'?Did you know that in superfluid helium, heat doesn't diffuse — it propagates as a coherent wave, known as the 'second sound'? This phenomenon gives it an effective thermal transport rate orders of magnitude higher than ordinary materials. Here's the crazy thing: this 'second sound' is not just a theoretical concept, but a real, observable phenomenon that has been confirmed by scientists.How Was the 'Second Sound' Discovered?Scientists at MIT have been studying the properties of superfluid helium, and their research has led to a major breakthrough. By using advanced imaging t...

"In a new study published in Nature Physics, researchers have developed the first controlled method for exciting and observing Kelvin waves in superfluid helium-4.

First described by Lord Kelvin in 1880, Kelvin waves are helical (spiral-shaped) waves that travel along the vortex lines, playing a vital role in how energy dissipates in quantum systems. However, they are difficult to study experimentally.

Creating a controlled setting to observe them has been the biggest challenge that the researchers overcame. Phys.org spoke to the first author of the study, Associate Prof. Yosuke Minowa from Kyoto University.

The discovery came about through serendipity. "We applied an electric field to a nanoparticle decorating a quantized vortex, hoping to translate the entire structure. Instead, we observed a clear wavy motion of the vortex core, namely Kelvin wave excitation. This unexpected result prompted us to shift our focus toward studying the excitation of Kelvin waves in-depth," said Prof. Minowa."