Scientists conducted a unique experiment with superfluid helium.
A unique experiment has allowed scientists to uncover the secrets of quantum superfluid matter. A team of physicists led by Samuli Autti of Lancaster University in the UK immersed a finger-sized sensor in a helium isotope cooled to near absolute zero and recorded its physical properties.
This is the first time that scientists have managed to get an idea of how the quantum universe can feel to the touch, and no one got serious frostbite and did not spoil the experiment.
"In practice, we don't know the answer to the question 'how does it feel to touch quantum physics?', "says Autty. "The conditions of the experiment are extremely complex, but now I can tell you what it would feel like if you could immerse your hand in this quantum system. No one has been able to answer this question for 100 years in the history of quantum physics. We show that, at least in superfluid helium-3, this question can be answered."
A superfluid is a state of matter that behaves like a liquid without viscosity or friction. There are two isotopes of helium that can create superfluidity. When cooled to temperatures just above absolute zero (-273.15 degrees Celsius), the bosons of the helium-4 isotope slow down so much that they overlap, forming a high-density cluster of atoms that behaves like a single "super-atom".
Helium-3 is slightly different. Its nuclei are fermions, a class of particles that rotate differently from bosons. When cooled below a certain temperature, the fermions bind into so-called Cooper pairs, each consisting of two fermions that together form a composite boson. These Cooper pairs behave exactly like bosons, and therefore can form superfluidity.
Autty and his team have been experimenting with superfluid fermionic helium-3 for some time and have found that while Cooper pairs are quite fragile, researchers can insert wire into it without destroying the pairs or disrupting the flow of superfluidity. So the team decided to develop a sensor to study the properties of the liquid in close proximity.
And the results were quite unusual. The surface of the liquid appears to form an independent two-dimensional layer that removes heat from the rod. The bulk of the superfluid beneath it behaves almost like a vacuum. Researchers have found that it is completely passive and not felt at all.
The only part of the liquid that interacted with the sensor was this two-dimensional surface layer. Access to the main mass is possible only if a huge amount of energy is added to it. The thermomechanical properties of a superfluid are completely determined by this two-dimensional layer.
"This liquid would feel like two-dimensional if you could dip your finger in it. The bulk of the superfluid appears to be empty, while heat flows in a two-dimensional subsystem along the edges of the bulk – in other words, along your finger," says Autti.
The scientists ' discoveries could dramatically change our understanding of superfluid helium-3 and have profound implications. Superfluid helium-3 is the purest known material and, as such, is of great scientific interest for studying collective states of matter, such as superfluids. Understanding the behavior of its two-dimensional layer can shed light on the behavior of quasiparticles, topological defects, and quantum energy states.
"These lines of research, "the researchers write,"have the potential to radically transform our understanding of such a universal macroscopic quantum system."
A unique experiment has allowed scientists to uncover the secrets of quantum superfluid matter. A team of physicists led by Samuli Autti of Lancaster University in the UK immersed a finger-sized sensor in a helium isotope cooled to near absolute zero and recorded its physical properties.
This is the first time that scientists have managed to get an idea of how the quantum universe can feel to the touch, and no one got serious frostbite and did not spoil the experiment.
"In practice, we don't know the answer to the question 'how does it feel to touch quantum physics?', "says Autty. "The conditions of the experiment are extremely complex, but now I can tell you what it would feel like if you could immerse your hand in this quantum system. No one has been able to answer this question for 100 years in the history of quantum physics. We show that, at least in superfluid helium-3, this question can be answered."
A superfluid is a state of matter that behaves like a liquid without viscosity or friction. There are two isotopes of helium that can create superfluidity. When cooled to temperatures just above absolute zero (-273.15 degrees Celsius), the bosons of the helium-4 isotope slow down so much that they overlap, forming a high-density cluster of atoms that behaves like a single "super-atom".
Helium-3 is slightly different. Its nuclei are fermions, a class of particles that rotate differently from bosons. When cooled below a certain temperature, the fermions bind into so-called Cooper pairs, each consisting of two fermions that together form a composite boson. These Cooper pairs behave exactly like bosons, and therefore can form superfluidity.
Autty and his team have been experimenting with superfluid fermionic helium-3 for some time and have found that while Cooper pairs are quite fragile, researchers can insert wire into it without destroying the pairs or disrupting the flow of superfluidity. So the team decided to develop a sensor to study the properties of the liquid in close proximity.
And the results were quite unusual. The surface of the liquid appears to form an independent two-dimensional layer that removes heat from the rod. The bulk of the superfluid beneath it behaves almost like a vacuum. Researchers have found that it is completely passive and not felt at all.
The only part of the liquid that interacted with the sensor was this two-dimensional surface layer. Access to the main mass is possible only if a huge amount of energy is added to it. The thermomechanical properties of a superfluid are completely determined by this two-dimensional layer.
"This liquid would feel like two-dimensional if you could dip your finger in it. The bulk of the superfluid appears to be empty, while heat flows in a two-dimensional subsystem along the edges of the bulk – in other words, along your finger," says Autti.
The scientists ' discoveries could dramatically change our understanding of superfluid helium-3 and have profound implications. Superfluid helium-3 is the purest known material and, as such, is of great scientific interest for studying collective states of matter, such as superfluids. Understanding the behavior of its two-dimensional layer can shed light on the behavior of quasiparticles, topological defects, and quantum energy states.
"These lines of research, "the researchers write,"have the potential to radically transform our understanding of such a universal macroscopic quantum system."
