Researchers have demonstrated for the first time a new technique to measure quantum excitation in superconducting materials with atomic precision. Detecting these excitations is an important step toward understanding exotic superconductors, which could help us improve quantum computers and possibly even pave the way to room temperature. superconductors.
Illustration of the Andreev reflection between a superconductor and an atomically sharp metal tip. Image credit: Aalto University / Jose Lado.
Superconductors are materials that have no electrical resistance, typically requiring extremely low temperatures. They are used in many fields, from medical applications to a central role in quantum computers. Superconductivity is caused by special bonding pairs of electrons known as Cooper pairs. Until now, the co-occurrence of Cooper pairs has been indirectly measured by mass macroscopic, but a new technique developed by researchers at Aalto University and Oak Ridge National Laboratory in the US has can detect their occurrence with atomic precision.
The experiments were performed by Wonhee Ko and Petro Maksymovych at Oak Ridge National Laboratory, with theoretical support from Professor Jose Lado of Aalto University. Electrons can “tunnel quantum” through energy barriers, jumping from system to system through space in a way that classical physics cannot explain. For example, if an electron pairs with another electron right at the point where the metal and the superconductor meet, it can form a Cooper pair that enters the superconductor while also “kick back” a particle. into the metal in a process known as Andreev reflection. The researchers looked for these Andreev reflections to detect Cooper pairs.
Professor Jose Lado. Photo: Aalto University / Evelin Kask.
To do this, they measured the current between the atomically sharp metal tip and the superconductor, as well as how the current depends on the separation between the tip and the superconductor. This allowed them to detect the amount of Andreev reflection back into the superconductor while maintaining an image resolution comparable to that of individual atoms. The results of the experiment correspond exactly to Lado’s theoretical model.
This atomic-scale Cooper pair detection test provides an entirely new way to understand quantum materials. For the first time, researchers can uniquely determine how the wave functions of Cooper pairs are reconstructed at the atomic scale and how they interact with atomic-scale impurities and obstacles. other.
“This technique establishes an important new methodology for understanding the internal quantum structure of exotic types of superconductors known as unique superconductors, potentially allowing us to solve problems,” says Lado. solve many open problems in quantum materials,” says Lado. Unusual superconductors are a potential fundamental building block for quantum computers and could provide a foundation for realizing room-temperature superconductivity. Cooper pairs have a unique internal structure in unusual superconductors that has so far been challenging to understand.
This discovery enables direct exploration of the states of Cooper pairs in unusual superconductors, establishing an important new technique for an entire family of quantum materials. It represents a major step forward in our understanding of quantum materials and helps advance work in the development of quantum technology.
Source: University of Aalto
