Pairing of Electrons in Artificial Atoms Discovered
Physicists from the Department of Physics at Universität Hamburg have made a groundbreaking observation in the field of quantum physics. They have successfully observed a quantum state that was theorized more than 50 years ago by Japanese theoreticians but had eluded detection until now. By manipulating an artificial atom on the surface of a superconductor, the researchers were able to pair electrons and create a basic version of superconductivity. This discovery has significant implications for the understanding and advancement of superconductivity in nanoscale structures, as well as its potential application in modern quantum computers.
Electrons, which typically repel each other due to their negative charge, play a crucial role in various material properties, including electrical resistance. However, when electrons are paired together, they become bosons and can coexist in the same space, unlike solitary electrons. This behavior of paired electrons is exhibited in materials with superconductivity, where an electrical current can flow without any resistance. Superconductivity has numerous practical applications, such as magnetic resonance imaging and magnetic field detectors. As electronic devices shrink in size, there is a growing interest in achieving superconductivity in smaller, nanoscale structures.
In their research, the physicists at Universität Hamburg focused on pairing electrons in an artificial atom called a quantum dot, which serves as the building block for nanostructured electronic devices. By constructing tiny cages from silver atoms and locking electrons inside, the researchers were able to couple these electrons with a superconductor, inheriting the tendency towards pairing. This successful pairing of electrons in the quantum dot aligns with the theoretical predictions made by Kazushige Machida and Fumiaki Shibata in the early 1970s.
The experimental signature of this quantum state, a spectroscopic peak at very low energy, was identified by the researchers and connected to the theoretical predictions. The discovery holds promise beyond the realm of fundamental physics, as recent research by teams from the Netherlands and Denmark has shown that this state can be utilized to suppress unwanted noise in transmon qubits, an essential component of modern quantum computers.
In a personal email, Kazushige Machida, one of the original theoreticians, expressed his gratitude to the researchers for confirming the existence of the quantum state. He noted the difficulty in directly detecting the state using traditional experimental methods and commended the ingenious approach employed by the researchers.
The research, titled “Proximity superconductivity in atom-by-atom crafted quantum dots,” was published in the journal Nature. The team behind the study includes Lucas Schneider, Khai That Ton, Ioannis Ioannidis, Jannis Neuhaus-Steinmetz, Thore Posske, Roland Wiesendanger, and Jens Wiebe. Their work represents a significant advancement in the field of quantum physics and opens up new possibilities for harnessing superconductivity in nanoscale structures and quantum computing.