Researchers claim that the strange behavior of high-temperature superconducting materials is `` possibly generated by quantum entanglement ''
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A superconducting material whose electrical resistance suddenly became zero when cooled to a very low temperature was discovered in 1911. In recent years, it has been put into practical use in various situations. Researchers who are investigating such superconducting materials argue that 'the strange behavior of superconducting materials may have been created by quantum entanglement .'
Incoherent strange metal sharply bounded by a critical doping in Bi2212 | Science
https://science.sciencemag.org/content/366/6469/1099
Superconductivity theory under attack
https://phys.org/news/2019-11-superconductivity-theory.html
Since the discovery of superconducting materials, it has been necessary to use liquid helium , which exists at an extremely low temperature of -269 ° C, for cooling to the superconducting state. However, since the discovery of high-temperature superconducting materials such as copper oxide superconductors that exhibit superconductivity at high transition temperatures in the 1980s, applications in a wider range than before have been expected.
The mechanism of superconductivity is explained by the BCS theory clarified by researchers at the University of Illinois in 1957. Based on the BCS theory, in order to realize the superconducting state, electrons are paired, and it is necessary to condense in the lowest energy state ( Bose = Einstein condensation ). This state occurs when the superconducting material is cooled below the transition temperature, allowing electrons to pass through the crystal without being blocked.
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However, research teams such as Stanford University and the National Institute of Advanced Industrial Science and Technology (AIST) pointed out that high-temperature superconducting materials may behave strangely even beyond the transition temperature. At temperatures slightly above the transition temperature, electrons do not behave as large independent particles like ordinary metals, and there are cases in which high-temperature superconducting materials transition to a state that behaves like a group.
Therefore, the research team conducted an experiment to observe the bismuth-based superconductor (Bi2212) using angle-resolved photoelectron spectroscopy (ARPES) . With ARPES, it is possible to investigate the electron direction, velocity, and scattering process by irradiating the sample with soft X-rays .
According to the research team, when the percentage of impurities added to Bi2212 was 19-20%, a transition from normal metal to metal that showed strange behavior was confirmed at a temperature slightly above the transition temperature. In this transition, it was shown that a 'discontinuous transition' in which the energy distribution of electrons changes rapidly, but as soon as the temperature falls below the transition temperature at which superconductivity occurs, the transition is discontinuous. It seems that the change of characteristics became continuous due to the loss of sex.
“In accordance with general physics principles, discontinuous behavior at high temperatures can occur even at low temperatures, according to the general co-author of the study, Leiden University professor Jan Zaanen . It is inconsistent with the calculation of ' Zaanen argues that, based on the results, strange metal behavior is occurring as a result of entanglement.
Based on the hypothesis that the strange behavior of high-temperature superconductors is caused by entanglement, Zaanen believes that the only way to calculate this strange behavior is to use a quantum computer. “In the world after 30 years, there is evidence that high temperature superconducting materials are fundamentally new forms of materials that are dominated by the consequences of entanglement,” Zaanen said.
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