Frustration, or frustration, is ubiquitous in nature and human society, and to a certain extent makes the world colorful. Geometry frustration in physics means that physical systems on certain specific geometries cannot simultaneously satisfy all competing interactions, leaving the system with a large number of degenerate energy states. As the temperature approaches absolute zero, classical thermodynamic fluctuations have been completely suppressed, and quantum fluctuations have begun to dominate. At this point, the combination of quantum mechanics and geometrical frustration can produce some strange quantum liquids in solids. In 1973, PW Anderson (Nobel Laureate in Physics in 1977) first pointed out theoretically that a quantum spin liquid can exist in a frustrated spin system with antiferromagnetic interactions on a triangular lattice. In the following decades, quantum spin liquids have attracted a wide range of theoretical studies, which led to the development of various theoretical models and computational methods, predicting many novel physical and physical effects. At the same time, experimental physicists are also trying to find and detect quantum spin liquids. However, to date, only a few candidate materials that may exist as quantum spin liquids have been discovered. Recently, Sun Yang and Yang Yifeng, researchers at the Institute of Physics, Chinese Academy of Sciences/Beijing National Laboratory for Condensed Matter Physics, expanded the category of quantum liquids in solids and proposed that they can exist in dielectrics with both geometrical and strong quantum fluctuations. A new quantum liquid - quantum electric-dipole liquid. At the same time, Sun Yang and his collaborators have found evidence that there may be quantum dipole liquids in a real material (BaFe12O19) through a series of experiments. Quantum fluctuations in dielectrics were originally discovered by KA Müller (Nobel Prize-winning physics 1987) and others in the 1970s when investigating the anomalous dielectric behavior of SrTiO3 at low temperatures. They believe that the quantum fluctuations make it impossible for the electric dipoles of the system to form long-range order when approaching absolute zero, and thus proposed the concept of a quantum paraelectric. Since then, people have found similar quantum paraelectrics in some perovskite oxides. In 2014, researchers Sun Yang, associate researcher Chai Yijun and doctoral student Shen Shipeng found a brand new family of quantum paraelectrics: hexagonal ferrite (Ba,Sr)Fe12O19. This kind of hexagonal ferrite has a layered crystal structure, in which the electric dipole originates from a tiny displacement of the off-center symmetry of the Fe3+ ion in the FeO5 double pyramidal unit. Due to quantum fluctuation effects, these weak electric dipoles are still unable to form long-range order at very low temperatures, exhibiting quantum paraelectric behavior. In traditional oxide ferroelectrics, the origin of electric dipoles usually satisfies the so-called d0 rule, that is, only non-magnetic ions whose d-orbital is empty can produce displacement-type polarisation. The electric dipole mechanism in the FeO5 double pyramid breaks the limit of the d0 rule, indicating that the displacement can be generated directly by the displacement of magnetic ions. The results of the relevant studies are published in Phys. Rev. B 90, 180404(R) (2014). Based on this work, Sun Yang et al. found that the FeO5 double pyramidal unit in BaFe12O19 happens to form a two-dimensional triangular lattice, resulting in a triangular grid electric dipole system. At the same time, theoretical calculations and experimental measurements show that there are antiferroelectric interactions between adjacent electric dipoles. Just as the antiferromagnet on a triangular grid has spin-suppression, the antiferroelectrics on the triangular grid are also facing a setback. Therefore, BaFe12O19 is a very special dielectric with both geometrical frustration and strong quantum fluctuations. The joint action of the two may result in the quantum liquid of the electric dipole. To test the existence of quantum electric dipole liquid, Sun Yang's research group cooperated with the Sun Xuefeng Research Group of the University of Science and Technology of China to accurately measure the thermal conductivity and specific heat behavior of BaFe12O19 single crystal at cryogenic temperatures (minimum to 66 mK). Experiments have found that in addition to conventional phonon thermal conduction, there is an additional contribution of low-energy element excitation to thermal conductivity below 650mK. At the low temperature limit, the thermal excitation of this extra element excitation is similar to that of the previously reported quantum spin liquid, with a very small energy gap. Since BaFe12O19 is a ferrimagnetic insulator (magnetic order temperature up to 720K), the contribution of electron and spin element excitation to thermal conductivity can be eliminated at very low temperatures, so the low-energy excitation of this mobility in BaFe12O19 is likely to be It corresponds to a quantum electric dipole liquid. It should be noted that although the quantum dipole liquid is like a quantum spin liquid, it consists of a large number of quantum dimers with remote quantum entanglement, but both may have significantly different characteristics and phase diagrams. This is because the interactions between spins and the interactions between electric dipoles have very different physical properties. Therefore, many theoretical models and theoretical predictions about quantum spin liquids cannot be directly applied to quantum electricity. Dipolar liquids require the development of new theoretical models and research methods. Quantum electric dipole liquid may not only contain abundant basic physics, but also is expected to be applied in the field of quantum information and quantum computing in the future. It can be expected that the theoretical research and experimental exploration of the quantum electric dipole liquid will open up a new research field. The above research results were published in Nature Communications 7, 10569 (2016). This work was supported by the National Natural Science Foundation, the Ministry of Science and Technology, and the Chinese Academy of Sciences project. 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