US scientists claim world's most accurate clock

US scientists said they have built the world's most precise clock, whose ticking rate varies less than two parts in one quintillion, or 10 times better than any other. The clock, made from the element ytterbium, could be used for technological advancements beyond timekeeping, such as navigation systems, magnetic fields and temperature. "The stability of the ytterbium lattice clocks opens the door to a number of exciting practical applications of high-performance timekeeping," National Institute of Standards and Technology physicist, and co-author of the study revealing the clock, Andrew Ludlow said in a statement. While mechanical clocks use the movement of a pendulum to keep time, atomic clocks use an electromagnetic signal of light emitted at an exact frequency to move electrons in cesium atoms. The physicists built their ytterbium clocks using about 10,000 rare-earth atoms cooled to 10 microkelvin (10 millionths of a degree above absolute zero) and trapped in an optical lattice made of laser light. Another laser that "ticks" 518 trillion times per second triggers a transition between two energy levels in the atoms. The clock's high stability is owed to the large number of atoms. The new clocks can achieve precise results very quickly. Technicians must average the current US civilian time standard, the NIST-F1 cesium fountain clock, for about 400,000 seconds (about five days) to obtain its best performance. But the new ytterbium clocks can achieve that same result in about one second of averaging time. The study was published in the journal Science.