Trapped ion

A trapped-ion qubit is a charged atom held in electric fields, and the amplitudes sit on two of its energy levels. The coherence time is read off that trap, and the papers file that number with the device rather than with a constant in the back of a book.

Keith likes the picture of an atom sitting still. Malcolm likes the line under it that says how long the phase survives, because a still atom with a scrambled sign prints an ordinary chance of 0 and of 1.