By introducing individual silicon atom 'defects' using a scanning tunnelling microscope, scientists at the London Centre for Nanotechnology have coupled single atoms to form quantum states.
Published today in Nature Communications, the study demonstrates the viability of engineering atomic-scale quantum states on the surface of silicon an important step toward the fabrication of devices at the single-atom limit.
Advances in atomic physics now allow single ions to be brought together to form quantum coherent states. However, to build coupled atomic systems in large numbers, as required for applications such as quantum computing, it is highly desirable to develop the ability to construct coupled atomic systems in the solid state.
Semiconductors, such as silicon, routinely display atomic defects that have clear analogies with trapped ions. However, introducing such defects deterministically to observe the coupling between extended systems of individual defects has so far remained elusive.
Now, LCN scientists have shown that quantum states can be engineered on silicon by creating interacting single-atom defects. Each individual defect consisted of a silicon atom with a broken, or "dangling", bond. During this study, these single-atom defects were created in pairs and extended chains, with each defect separated by just under one nanometer.
Importantly, when coupled together, these individual atomic defects produce extended quantum states resembling artificial molecular orbitals. Just as for a molecule, each structure exhibited multiple quantum states with distinct energy levels.
The visibility of these states to the scanning tunneling microscope could be tuned through the variation of two independent parameters the voltage applied to the imaging probe and its height above the surface.
The study was led by Dr Steven Schofield, who said: "We have created precise arrays of atomic defects on a s
|Contact: Clare Ryan|
University College London