Radioactive Qubits

Trapped and laser-cooled ions are a popular choice to serve as quantum bits. Ideally, these ions should have an internal structure that allows robust manipulation of the ions’ states, as well as laser-cooling transitions at visible wavelengths. Only the barium-133 ion satisfies both these criteria. The one hitch is that barium-133 is radioactive, with a half-life of 10.5 years, which means it isn’t naturally occurring. Researchers from the University of California, Los Angeles, have managed for the first time to trap and cool a single synthetically produced barium-133 ion. The team also measured the ion’s spectrum, the details of which are needed for preparing and manipulating the qubit states of these ions.