How could you improve the precision of an atomic clock? Use two!

Atomic clocks were first developed in the 1940s and 50s. Electrons in an atom are constantly vibrating between two discrete energy states. The speed at which this happens is individual to every atom and it was discovered that this could be harnessed as an incredibly accurate way of keeping and measuring time. The National Institute of Standards and Technology (NIST) have used the element Caesium to standardise clocks and measuring devices all over the world since 1967, one second being defined as 9,192,631,770 vibrations of the Caesium133 electrons. This is accurate to 30 billionths of a second per year!

However, scientists at NIST have started focussing on the element Ytterbium and have used two separate versions of this clock in combination with each other to increase the stability and precision of the process. This means that each transition of the electrons is exactly the same as any before or after it. In the older versions of the atomic clock there was always aproblem with the very small imperfections in the transitions known as ‘noise’ but this double clock system eliminates this problem making it accurate to 1.5 parts in a quintillion (18 zeros!)

Applications of this new clock could be far-reaching as it is thought that the design should make it possible to manufacture a much smaller machine, making it portable for use outside laboratories for the first time. It will help in the search for dark matter and to test ideas about fundamental universal constants. Because of the portable aspect it could be transported all over the world to standardise other instruments and most exciting of all it is thought that it could be involved in space travel to try to prove more accurately Einstein’s theory of general relativity.