 Visible light waves oscillate faster than microwaves , and therefore optical clocks can be more precise than caesium atomic clocks . The Physikalisch @-@ Technische Bundesanstalt ( PTB ) is working on several such optical clocks . The model with one single ytterbium ion caught in an ion trap is highly accurate . The optical clock based on it is exact to 17 digits after the decimal point . A pair of experimental atomic clocks based on ytterbium atoms at the National Institute of Standards and Technology ( NIST ) has set a new record for stability . NIST physicists report in the August 22 , 2013 issue of Science Express that the ytterbium clocks ' ticks are stable to within less than two parts in 1 quintillion ( 1 followed by 18 zeros ) , roughly 10 times better than the previous best published results for other atomic clocks . The clocks would be accurate within a second for a period comparable to the age of the universe . 
