The NPL-CsF2 Atomic clock is accurate to within two 10 million billionths of a second, yes this has been confirmed by British and US scientist that an atomic clock at National Physical Laboratory near London is the most accurate long-term timekeeper in the world, said the NPL. NPL-CsF2 is a standard cesium fountain clock for International Atomic Time and Universal Coordinated Time.
The analysis of the clock conclude that the clock loses 1 billionth of a second every two months thus showing its unprecedented accuracy. The Cesium clocks are usually expected to lose or gain a second over tens of millions of years. With improvements to the cesium fountain, the models and numerical calculations improved the accuracy of the U.K.’s cesium fountain clock NPL-CsF2, by reducing the uncertainty to 2.3 × 10-16 the lowest value for any primary national standard till date.