12 February 2013 Catching and twisting a single spin with light in Nature Nanotech

Nanomanipulation of an artificial atom

ICFO researchers demonstrate 3D optical manipulation of a single electron spin in solution. Researchers in the group led by ICFO Prof. Romain Quidant, in collaboration with Prof. Frank Koppens at ICFO, CSIC (Prof. García de Abajo) and Macquarie University in Australia, have developed a new technique, similar to the MRI but with a much higher resolution and sensitivity, which has the ability to scan individual cells. The paper published in Nature Nanotech, and highlighted by Nature, explains how this was accomplished using artificial atoms, diamond nanoparticles doped with nitrogen impurity, to probe very weak magnetic fields such as those generated in some biological molecules.

Individual atoms are structures that are highly sensitive to their environment, with a great ability to detect nearby electromagnetic fields. The challenge these atoms present is that they are so small and volatile that in order to be manipulated, they must be cooled to temperatures near the absolute zero. This complex process requires an environment that is so restrictive that it makes individual atoms unviable for potential medical applications. Artificial atoms used by Quidant and his team are formed by a nitrogen impurity captured within a small diamond crystal. \"This impurity has the same sensitivity as an individual atom but is very stable at room temperature due to its encapsulation. This diamond shell allows us to both move and rotate the nitrogen impurity. In addition, because such control is achieved in solution, our technique is compatible with measurements on a living cell\" argues Dr. Quidant.

To trap and manipulate these artificial atoms, researchers use laser light. The laser works like tweezers, leading the atoms above the surface of the object to study and extract information from its tiny magnetic fields.

The emergence of this new technique could strongly benefit the field of medical imaging, providing a new class of information that could contribute to early detection of diseases, and thus a higher probability for successful treatment.

This research has been possible thanks to the support of the private foundation Cellex Barcelona.