Researchers at the National Institute of Standards and Technology (NIST) created grids of tiny clusters of atoms known as quantum dots and studied what happens when electrons dive into these archipelagos of atomic islands. Measuring the behavior of electrons in these relatively simple configurations promises insights into how electrons behave in complex real-world materials and could help researchers design devices that enable powerful quantum computers and other innovative technologies.
In the work published in Communications Nature, the researchers made multiple 3-by-3 grids of precisely spaced quantum dots, each comprising one to three phosphorus atoms. Attached to the grids were electrical wires and other components that allowed electrons to flow through them. Grids provided playgrounds in which electrons could behave under near-ideal, textbook conditions, free from the confusing effects of real-world materials.
The researchers injected electrons into the grids and watched how they behaved as the researchers varied conditions such as the spacing between the dots. For grids where the points were close together, the electrons tended to spread out and act as waves, essentially existing in several points at once. When the points were far apart, they sometimes became trapped in single points, like electrons in materials with insulating properties.
Advanced versions of the grid would allow researchers to study the behavior of electrons in controllable environments in a level of detail impossible for the world’s most powerful conventional computers to accurately simulate. It would open the door to real ‘analog quantum simulators’ that unlock the secrets of exotic materials such as high-temperature superconductors. It could also provide hints on how to create materials, such as topological insulators, by controlling the geometry of the array of quantum dots.
In the related work just published in ACS Nano, the same NIST researchers improved their method of fabrication so that they can now reliably create a series of identical, evenly spaced dots with exactly one atom each, leading to the even more ideal environments needed for a fully accurate quantum simulator. Researchers have focused on building such a simulator with a larger grid of quantum dots: a 5 × 5 matrix of dots can produce rich electronic behavior that is impossible to simulate even in the most advanced supercomputers.