The most familiar liquid to all of us is of course water, which is made up of a huge amount of molecules of hydrogen and oxygen. These molecules are in constant interaction with each other through molecular forces called dipole forces. Liquids such as water are well described by classical Newtonian theory. Physical theories, on the other hand, predict that when an atomic and molecular liquid is cooled to very low temperatures, close to absolute zero, the liquid will change its properties, and become a quantum liquid. Such a liquid would have exotic properties explained by quantum theory. For example, it can completely lose its viscosity and flow without friction with the container, a phenomenon called superfluidity.
Unfortunately water cannot be a quantum liquid because it freezes and becomes solid at much higher temperatures, so scientists study gases of atoms and other molecules, which can be cooled sufficiently until quantum theory becomes relevant (examples are cold helium atoms liquid, or chromium atom gas or Magnetic field dispersion). All of these are natural atoms of elements in nature.
About fifty years ago, theoretical physicists proposed that electronic quantum fluids could be formed within thin layers of semiconductor materials by creating "artificial atoms" from free electrons that arouse in these layers with light. These artificial atoms are called "excitons". These excitons behave much like natural atoms, but unlike atoms, they are artificially created within electronic and electro-optical devices and can therefore be integrated into semiconductor technology, which is the leading technology in modern microelectronics and integrated circuits.
 Another difference between true excitons and atoms is that excitons live only for a fraction of a second, then decay and emit light. This feature limits the possibility of producing stable exciton fluid, but in a series of works published in recent years by researchers from the Hebrew University (and at the same time at the Weizmann Institute), evidence has accumulated that stable and long-lasting diphthonic fluid can indeed be formed in electro-optical devices made of special structures. Minutes of semiconductors, through dipular forces that are very similar to forces in real opaque liquids.
In the laboratory of Prof. Ronen Rapaport, from the Spice Institute of the Faculty of Natural Sciences, a paper was published this year in the scientific journal Nanoletters in which the scientists showed evidence that the liquid formed is probably in a "dark" state, where the excitons are in a quantum state. As a result the liquid formed is very dense and may be similar in its properties to a natural quantum liquid of cold liquid helium, known to science and technology for almost a century. This experiment is the first experimental support for a theory from about ten years ago that predicted the existence of dark quantum exciton fluids.
These new results open a window for a better understanding of multi-particle quantum systems, systems that are very challenging for theoretical understanding because of their complexity, and form the frontier of theoretical knowledge in quantum theory. Understanding the properties of cold excitatory liquids may in the future allow such exotic liquids to be incorporated within electronic components and to use their unique properties.

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