NIST physicists have confined graphene quantum dots into a tiered, cake-like structure of electrons, proving theoretical speculations, and promising applications for quantum computing.
Ersatz quantum processors exist and some models have been commercialized already. However, we can’t tag them as “true quantum computers” until they surpass conventional computers’ speed to perform intricate calculations.
Graphene is regarded by some as the key material that will drive the much-heralded electronic revolution through universal quantum computing.
One of the most promising routes to quantum computers is what’s called quantum dots, bidimensional superconducting structures, specifically those made from graphene.
Quantum Interactions of Electrons is a Piece of Cake
Scientific experiments have confirmed the potential of graphene time and time again.
Physicists and engineers devote much time to investigate electron-electron interactions and discover some new electronic properties in graphene along the way.
In a new study, researchers at the National Institute of Standards and Technology (NIST) have spatially and magnetically confined electrons within graphene atoms into “wedding-cake”-like nanostructures.
The experiment “confirms how electrons interact in a tightly confined space according to long-untested rules of quantum mechanics. The findings could also have practical applications in quantum computing.”
Scientists have to confine quantum dots in space to work with them, but NIST researchers thought of applying a magnetic field to see how electrons orbiting quantum dots would behave.
Using a scanning tunneling microscope, the team found that electrons packed together more and arranged themselves into concentric rings that alternate between conducting and insulating energy levels, shaped like a tiered cake.
“This is a textbook example of a problem — determining what the combined effect of spatial and magnetic confinement of electrons looks like — that you solve on paper when you’re first exposed to quantum mechanics, but that no one’s actually seen before… In previous experiments using other materials, quantum dots were buried at material interfaces so no one had been able to look inside them and see how the energy levels change when a magnetic field was applied,” said NIST’s Joseph Stroscio.
According to the research paper, the new experiment also opens the door to probe the potential of graphene as a relativistic quantum simulator.
Particles of a “quantum-relativistic matter” move at speeds near to the speed of light, or what’s called “relativistic speed”.
Electrons within graphene atoms have this property and exhibit photon-like behavior as if they were massless, and the present study from NIST creates “a table-top experiment to study strongly confined relativistic matter.”
However, the magnetic confinement of electrons doesn’t work in a room-temperature setting. For the emerging phenomenon to take place, NIST researchers have to subject the graphene quantum dots to near absolute zero temperatures.