Paul van Gerven
19 December 2019

Work on a particular type of quantum computer may lead to new imaging technology capable of atomic-scale resolution. By measuring nuclear spin interactions in a 27-atom diamond, researchers at Qutech have been able to obtain a complete 3D structure of it. Eventually, the technique might be used to image individual molecules, such as proteins.

Current spin-based imaging techniques such as magnetic resonance imaging (MRI) yield information about large amounts of atoms over large volumes – in other words, an average. It’s not possible to image individual molecules or other nanoscale structures.

A Qutech team, however, found that so-called nitrogen vacancy (NV) centers – a nitrogen atom replacing two carbon atom in diamond, normally used to make qubits – also make good quantum sensors. “The NV center is sensitive enough to resolve the tiny signals of individual nuclei. But for imaging complex samples such as molecules, just detecting nuclear spins is not enough. You need to precisely determine the position of each spin in the sample, and that’s what we set out to do,” explains Tim Taminiau, lead author of the study published in Nature.

Qutech diamond
Credit: Ernst de Groot, Qutech

“We developed a method to obtain the 3D structure of complex spin systems,” says co-author Joe Randall. “Each nuclear spin feels the magnetic field from all the other nuclear spins. These interactions depend on the precise positions of the atoms and therefore encode the spatial structure. For example, two atoms that are closer to each other tend to interact more strongly. We developed methods to precisely measure these interactions and to transform them into a complete 3D image with atomic resolution.”

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Thus, the researchers were able to image a cluster of 27 carbon-13 atoms. The next step would be to detect samples outside the diamond by bringing NV centers close to the surface.