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Engineers crack 58-year-old puzzle on way to quantum breakthrough:

[...] Generating magnetic fields requires large coils and high currents, while the laws of physics dictate that it is difficult to confine magnetic fields to very small spaces—they tend to have a wide area of influence. Electric fields, on the other hand, can be produced at the tip of a tiny electrode, and they fall off very sharply away from the tip. This will make control of individual atoms placed in nanoelectronic devices much easier.

[...] The researchers had originally set out to perform nuclear magnetic resonance on a single atom of antimony—an element that possesses a large nuclear spin. One of the lead authors of the work, Dr. Serwan Asaad, explains: "Our original goal was to explore the boundary between the quantum world and the classical world, set by the chaotic behaviour of the nuclear spin. This was purely a curiosity-driven project, with no application in mind."

"However, once we started the experiment, we realised that something was wrong. The nucleus behaved very strangely, refusing to respond at certain frequencies, but showing a strong response at others," recalls Dr. Vincent Mourik, also a lead author on the paper.

[...] Dr. Asaad continued: "What happened is that we fabricated a device containing an antimony atom and a special antenna, optimized to create a high-frequency magnetic field to control the nucleus of the atom. Our experiment demands this magnetic field to be quite strong, so we applied a lot of power to the antenna, and we blew it up!"

[...] "Normally, with smaller nuclei like phosphorus, when you blow up the antenna it's 'game over' and you have to throw away the device," says Dr. Mourik."But with the antimony nucleus, the experiment continued to work. It turns out that after the damage, the antenna was creating a strong electric field instead of a magnetic field. So we 'rediscovered' nuclear electric resonance."

After demonstrating the ability to control the nucleus with electric fields, the researchers used sophisticated computer modelling to understand how exactly the electric field influences the spin of the nucleus. This effort highlighted that nuclear electric resonance is a truly local, microscopic phenomenon: the electric field distorts the atomic bonds around the nucleus, causing it to reorient itself.

Journal Reference,:
Serwan Asaad, Vincent Mourik, Benjamin Joecker, Mark A. I. Johnson, Andrew D. Baczewski, Hannes R. Firgau, Mateusz T. Mądzik, Vivien Schmitt, Jarryd J. Pla, Fay E. Hudson, Kohei M. Itoh, Jeffrey C. McCallum, Andrew S. Dzurak, Arne Laucht1, Andrea Morello. Coherent electrical control of a single high-spin nucleus in silicon, Nature (2020). DOI: 10.1038/s41586-020-2057-7 , https://nature.com/articles/s41586-020-2057-7

Original Submission