Quantum spin qubit created from phosphorus

Ars Technica : Because electron spin is a simple binary state—either up or down—it has potential for quantum computing, but systems for maintaining and controlling spin states have been hard to implement. A team of researchers from the University of New South Wales in Sydney, Australia, has achieved relatively long-duration electron spin states using phosphorus embedded in silicon. The researchers found that phosphorus, with just a single electron in its outer shell, is an excellent host for single spins, while crystals of silicon, being next to phosphorus in the Periodic Table, is an excellent host for phosphorus atoms. Working at just 0.3 K and in a strong magnetic field, the researchers used microwave pulses to initialize the electron spin state, which remained coherent for up to 0.2 ms. That duration is more than long enough for the operation of electronics, and the setup serves as proof of concept for the use of spin-based quantum computing systems.