Superconductors are materials that do not have any resistance, and usually require very low temperatures to achieve the desired properties. They are used in a wide range of fields, from medical applications to the core role of quantum computers. Superconductivity is caused by specially linked electron pairs called Cooper pairs So far, the appearance of Cooper pairs has been measured indirectly through macro methods, but a new technology developed by researchers at the University of Alto and Oak Ridge National Laboratory in the United States can detect their appearance with atomic accuracy
The experiment was conducted by wonhee Ko and petro maksymovych of Oak Ridge National Laboratory with the theoretical support of Professor Jose Lado of Alto University. Electrons can cross the energy barrier through quantum tunnels, jumping from one system to another in a way that cannot be explained by classical physics. For example, if an electron is paired with another electron at the junction of metal and superconductor, it can form a Cooper pair entering the superconductor and "kick" another particle back to the metal. This process is called Andreev reflection. The researchers detected Cooper pairs by looking for these Andreev reflections.
To do this, they measured the current between an atomically sharp metal tip and a superconductor, and how the current depends on the spacing between the tip and the superconductor. This allows them to detect the amount of Andreev reflection returning to the superconductor while maintaining an imaging resolution comparable to that of a single atom. The experimental results are completely consistent with Rado's theoretical model.
The experimental detection of Cooper pairs at the atomic scale provides a new method for understanding quantum materials. For the first time, researchers were able to uniquely determine how the wave functions of Cooper pairs are reconstructed at the atomic scale, and how they interact with impurities and other obstacles at the atomic scale.
This technology has established a key new method for understanding the internal quantum structures of foreign types called unconventional superconductors, which may allow us to solve various open problems in quantum materials. Unconventional superconductor is a potential basic component of quantum computer, which can provide a platform to realize superconductivity at room temperature. Cooper pairs have unique internal structures in unconventional superconductors. So far, it is very difficult to understand these structures.
This discovery enables researchers to directly detect the state of Cooper pairs in unconventional superconductors, and establishes a key new technology for the entire quantum material family. It represents a big step forward in the understanding of quantum materials in the scientific community, and helps to promote the development of quantum technology.