Controlled ‘wobble’ created in nucleus of single atom to store quantum data

What’s the safest place to store important information? No, it’s not your external hard drive or some secret cloud application.

Some researchers believe that when it comes to storing quantum information, the most secure spot is probably the nucleus of an atom.

Quantum information is the data inside a quantum computer, which is stored and processed in the form of qubits.

A new study reveals that it is possible to store quantum information inside the nucleus of an atom where it will remain safe from all kinds of external disturbances. Such storage techniques can pave the path for highly secured quantum computing applications.

The study authors at the Delft University of Technology (TU Delft) performed an interesting experiment involving a Titanium atom (Ti-47) to store and read quantum information from its nucleus.

“This experiment gives humans influence on the state of matter on an unimaginably small scale. To me, that alone makes it worth the effort,” Sander Otte, one of the researchers and a physics professor at TU Delft, said .

Reading a nucleus is challenging

According to the researchers, the spin state or direction of the spin of a nucleus can be used to hold quantum information.

“This magnetism, the “spin” in quantum language, 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 study authors said.

However, even if you store quantum information inside the spin of a nucleus, it’s challenging to read and manipulate the stored information as the nucleus has a tiny size and is influenced by the activity of surrounding particles.

For instance, there is a weak connection between the nucleus and the orbiting electrons of an atom called the hyperfine interaction. Due to this, the spin of an electron can slightly affect the nucleus’ spin, making it difficult to read the stored information .

“Accessing the coherent dynamics involving the nucleus remained challenging, due to its weak coupling to the tunneling electrons,” the study authors note .

However, the new study suggests that there’s a way to control and harness this interaction to read quantum information.

Triggering a wobble inside a nucleus

The researchers suggest that to read the quantum information, it is important to match the spin of the external electrons with that of the nucleus. The only way to achieve this is by disturbing the electron spin movement by creating a wobble inside the atom.

“We used a voltage pulse to push the electron spin out of equilibrium, after which both spins (of electron and the nucleus) wobbled together for a fraction of a microsecond,” Lukas Veldman, first author of the study and a PhD candidate at TU Delft, said.

Then they inserted the needle of a scanning tunneling microscope to read the stored information from the electron interacting with the nucleus.

The researchers also performed calculations to check whether the controlled interaction between the electron and the nucleus of the Titanium atom resulted in the loss of information.

Their experiment confirmed that quantum information remained safe. It successfully demonstrates that “The efficient shielding from the environment makes the nuclear spin a viable candidate for holding quantum information,” the researchers note.

The study is published in the journal Nature Communications .