Researchers have successfully created electrically defined quantum dots in zinc oxide (ZnO) heterostructures, marking a significant milestone in the development of quantum technologies.
Details of their breakthrough were published in the journal Nature Communications on November 7, 2024.
Quantum dots, tiny semiconductor structures that can trap electrons in nanometer-scale spaces, have long been studied for their potential to serve as qubits in quantum computing. These dots are crucial for quantum computing because they allow scientists to control the behavior of electrons, similar to how a conductor might control a current of water flowing through pipes.
Until now, most research has focused on materials such as gallium arsenide (GaAs) and silicon. However, zinc oxide, a material known for its strong electron correlation and excellent spin quantum coherence, had not yet been explored for use in electrically defined quantum dots, i.e., those created and controlled using electrical methods.
In this study, the research team was able to manipulate the internal states of quantum dots in zinc oxide using precise voltage control -- like adjusting the dials on a radio to fine-tune a signal. This innovation allowed them to observe the Coulomb diamond, a key characteristic of quantum dots, providing insights into the behavior of electrons trapped inside.
"The Coulomb diamond is like a fingerprint that helps identify the unique 'personality' of each quantum dot," points out Tomohiro Otsuka, an associate professor at Tohoku University and corresponding author of the paper. "By using zinc oxide, we're opening up new frontiers developing efficient and stable qubits, a cornerstone for quantum computing."
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