The clock, which is based on a single aluminium ion, could remain accurate to within one second over 3.7 billion years. The previous record was held by a clock with one mercury ion, which was good to one second in 1.7 billion years.My, these are some mind-boggling figures.
I thought that one 27Al+ ion should not take much space. But then, they needed another “logic ion”, 25Mg+. And a vacuum chamber. And two lasers. (Not three lasers, as in earlier model which used Al+/Be+ pair, so I presume the new clock is more compact.) I couldn’t find in the preprint what are the dimensions of the whole contraption. However, the NIST press release features the photo of one of the authors, Chin-wen Chou, together with the famous clock. The caption says that
The ion is trapped inside the metal cylinder (center right).
Not exactly wristwatch size but easily fits in Big Ben.