A landmark paper published today in the journal Nature ("High-fidelity readout and control of a nuclear spin qubit in silicon"), describes how to write and read quantum information with record-setting accuracy using the nuclear spin, or magnetic orientation, of a phosphorus atom in a silicon transistor – similar to silicon chips used in modern electronics.

 

The nucleus of a phosphorus atom is a very, very weak magnet, and can be imagined as a compass needle that can point north or south. These north or south positions are equivalent to the zero and one of binary code, which governs classical computing. In this experiment, the researchers controlled the direction of the nucleus, in effect “writing” an arbitrary value onto its spin, and were then able to “read” the value out. They observed quantum oscillations of the spin between north and south, and all the quantum superpositions of those two directions – where the spin exists in both states simultaneously.