Physics from Spain created the light liquid in the Universe

© ICFO/ Povarchik Studios BarcelonaТак the artist presented his quantum liquid, created by Spanish physicistsPhysics from Spain created the light liquid in the Universe© ICFO/ Povarchik Studios Barcelona

Scientists from Catalonia «brought up» a drop of quantum liquid, which have unusual properties and have the lowest density, according to a paper published in the journal Science.

«Our potassium drops largely similar to the regular drops of water – they have a well-defined size, shape and weight, regardless of where it was placed. On the other hand, they exist only at very low temperatures and have a quantum nature,» says Cesar Cabrera (Cabrera Cesar) from the Institute of science and technology, Barcelona (Spain).

As noted by a physicist, this quantum liquid has a record of high sparseness – it contains the minimum number of atoms required in order that the drops do not lose their shape and not turn into a gas. In other words, all its particles linked to each other and the nature of their movement in space depends on where you are located and how their «neighbors».

Cabrera and his colleagues have created this unusual substance, trying to answer a simple question — how to behave in gases and liquids at very low temperatures, and where is the point when the dense gas turns into liquid, and the diluted fluid is in the gas.

To answer this question, physicists have created a third substance – the so-called condensate Bose-Einstein, cooled cloud of atoms of potassium-39 to a temperature close to absolute zero. It is a unusual in its properties is a form of matter similar to gas and liquid, which behaves as a single gigantic atom and has a typical «atomic» properties.

In «normal» state of the condensate Bose-Eistein, says Cabrera, behaves more like a gaseous substance – it expands and tends to fill the whole vessel, where it is located. As shown by the experiences of the Spanish explorers, the collision of two such clouds of gas leads to very interesting consequences – it creates a group of several tiny droplets of quantum liquids.

Atoms in its drops are distributed so that they are separated a maximum distance, but quantum communication between will not disappear. Thanks to these connections a drop of quantum liquid of a mixture of condensates Bose-Einstein retain their shape and not turn into a gas.

«These drops are amazing objects of the macrocosm — despite the fact that they consist of thousands of atoms, their behavior is fully specified by the quantum fluctuations and correlations,» adds Letitia, Tarruell (Leticia Tarruell), a colleague of Cabrera.

This liquid has an extremely low density – about a hundred million times more diluted than ordinary water, and about a million times less then in conventional air, and also has another unusual property. Its atoms are constantly moving, even at near-zero temperatures, obeying Heisenberg’s uncertainty principle and other laws of quantum mechanics.

How to tell scientists that such a high degree of sparseness of the quantum liquid was a surprise to them — theoretical calculations showed that it was supposed to be about two times more dense, and the droplet size had to be almost three times less. Given the huge number of atoms in these droplets, calculate their behavior at the quantum level is impossible, which does not allow to give a definite explanation for this unusual discrepancy between theory and experiment.

For this reason, their properties and secrets, according to physicists, you can uncover watching the formation and interaction of these drops in the real world. These experiments may help physicists not only to find an explanation for their strange size and density, but also to reveal the principles that govern the interactions of tens or hundreds of quantum objects with each other, for example, in liquid helium or in the depths of neutron stars.