This is a new type of super accurate clock
invented by a team of physicists in Boulder Colorado
. Scott Diddams
was the head of the team.
This clock is too expensive to replace your current alarm clock, but will have important uses in physics. It would be expected to gain or lose less than a second in fifteen billion years.
The clock is based on the oscillation of a cooled mercury ion, and the cycles are counted by a very precise laser.