Researchers at the National Institute of Standards and Technology (NIST) have created grids of tiny clusters of atoms known as quantum dots and studied what happens when electrons dive into these atomic island archipelagos. Measuring the behavior of electrons in these relatively simple configurations promises deep insights into how electrons behave in complex real-world materials and could help researchers design devices that make powerful quantum computers and other possible innovative technologies.
In a book published in Nature Communication, the researchers created 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 pass through them. The grids provided playing fields in which electrons could behave under near-ideal, textbook-like conditions without the confusing effects of real-world materials.
The researchers injected electrons into the grids and observed how they behaved when the researchers varied conditions such as the spacing between the dots. For grids in which the points were close, the electrons tended to propagate and act like waves, essentially existing in multiple places at once. When the dots were far apart, they were sometimes trapped in individual dots, 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 that would be impossible for the world’s most powerful conventional computers to accurately simulate. This would open the door to full-fledged “analog quantum simulators” that would reveal the secrets of exotic materials such as high-temperature superconductors. It could also provide guidance on how to create materials, such as topological insulators, by controlling the geometry of the quantum dot network.
In a related work just published in ACS Nano, the same NIST researchers improved their fabrication method so that they can now reliably create an array of identical, equally spaced points with exactly one atom each, leading to even more ideal environments needed for a perfectly accurate quantum simulator. The researchers aim to create such a simulator with a larger quantum dot grid: a 5×5 quantum dot array can produce rich electronic behavior that is impossible to simulate even in the most advanced supercomputers.
Xiqiao Wang et al, Experimental realization of an extended Fermi-Hubbard model using a dopant-based 2D quantum dot array, Nature Communication (2022). DOI: 10.1038/s41467-022-34220-w
Jonathan Wyrick et al, Enhanced Atomic Precision Fabrication by Adsorption of Phosphine into Engineered Dangling Bonds on H – Si Using STM and DFT, ACS Nano (2022). DOI: 10.1021/acsnano.2c08162
Provided by the National Institute of Standards and Technology
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