Superposition is a quantum mechanical phenomenon that allows for one particle to exist in many positions or states at the same time. This is something researchers are working to take advantage of for use in quantum computers. The qubits in a quantum computer are in a superposition, which allows one particle to exist as both 0 and 1, as opposed to electronic bits that are 0 or 1. A material many researchers have been looking at for use in quantum computers is diamond, thanks to how the spin states of imperfections are held. This led some researchers to an interesting experiment.
Researchers at the University of Southern California, Iowa State University, University of California, Santa Barbara, and Delft University of Technology in the Netherlands have created a functional quantum computer within a diamond. It is not very powerful, with only two qubits, but has proven itself to be a quantum computer, and has one interesting property. Instead of using electrons as the qubits, which is fairly common when dealing with diamond, the researchers used nitrogen nuclei, from the diamond’s imperfections. While a nucleus will be a slower qubit than an electron, it is far more stable and offers protection from decoherence. This is the first solid-state computing system to have such protection.
To verify the diamond is indeed a functional quantum computer, the researchers tested it with Grover’s algorithm. In classical mechanics, if you are told to find something in a list of four elements, on average you will find it after the second element you look at. What Grover’s algorithm does is allow quantum computers to find the correct entry in the four item list on the first try, every time. When the diamond was tested, it found the correct entry the first time 95% of the entire. Not quite perfect, but close enough to confirm the quantum computer is functional.