Researchers from Delft University of Technology and Karlsruhe Institute of Technology (KIT) have initiated a controlled movement in the heart of an atom, causing the atomic nucleus to interact with one of the electrons in the outermost shells of the atom. This electron could be manipulated and read out through the needle of a scanning tunneling microscope. The research offers prospects for storing quantum information inside the nucleus, where it is safe from external disturbances.
The team studied a single titanium atom - a Ti-47 atom, that has one neutron less than the naturally abundant Ti-48, which makes the nucleus slightly magnetic. This magnetism, or the 'spin', can be seen as a sort of compass needle that can point in various directions. The orientation of the spin at a given time constitutes a piece of quantum information.
The nucleus of an atom floats inside a (comparatively) large void far away from the orbiting electrons, separate from its environment. But there is one exception: due to the extremely weak 'hyperfine interaction', the nuclear spin can be influenced by the spin of one of the electrons.
However, this is not easy, as the team explained, because the hyperfine interaction is so weak that it is effective only in a very small, precisely tuned magnetic field.
Once all experimental conditions were met, the researchers used a voltage pulse to push the electron spin out of equilibrium, after which both spins wobbled together for a fraction of a microsecond.
Alongside the experiments, the scientists performed calculations that reproduced the observed fluctuations surprisingly well. The strong agreement between observations and predictions demonstrates that no quantum information is lost during the interaction between electron and nucleus.
The efficient shielding from the environment makes the nuclear spin a viable candidate for holding quantum information. The current research may bring that application one step closer. But that is not what primarily drives the researchers, that said: "This experiment gives humans influence on the state of matter on an unimaginably small scale. To me, that alone makes it worth the effort."