Most Accurate Clock In The World: New Strontium Clock Is So Precise It Won't Change One Second in Five Billion Years
An experimental atomic clock that packs trillions of ticks into a second, and is so accurate that it won't add or shed a second in billions of years, is being touted by the National Institute of Standards and Technology (NIST) as the most accurate clock in the world Described in a new paper, "A new generation of atomic clocks: Total uncertainty and instability at the 1018 level," in Wednesday's on-line issue of Nature, the strontium lattice clock is about 50 percent more precise than the record-holder thus far, the quantum logic clock, which ran on aluminum ions.
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The strontium clock is so precise it would neither gain nor lose one second in about five billion years, according to a press release. It may also replace the current U.S. civilian time standard clock, the NIST-F1 cesium fountain clock, which it already surpasses in accuracy, its developers claim. The clock is in a laboratory at the University of Colorado Boulder, which helped develop the almost awesomely accurate timepiece.
Making this staggering accuracy possible is a lattice of lasar light holding aloft a column of only few thousand atoms of strontium. The chemical element strontium — symbol Sr and atomic number 38 — is an alkaline, soft silver-white metal that turns yellow when exposed to air. This is not the first time engineers have built a clock out of strontium: They did it in 2005, and again last year. This time, though, the engineers were able to include new, ultra-stable red lasers that bathe the strontium atomos at the precise frequency that throws a switch between energy levels, and allowing for detection of the strontium's "ticks" — 430 trillion per second.
The strontium clock's stability — the extent to which each tick matches the duration of every other tick — is about the same as NIST's ytterbium atomic clock, trotted out in August of 2013. Stability determines in part how long an atomic clock must run to achieve its best performance through continual averaging, the paper's authors explained. The strontium and ytterbium lattice clocks are so stable that in just a few seconds of averaging they outperform other types of atomic clocks that have been averaged for days.
The current international definition of units of time requires the use of cesium-based atomic clocks, introduced in the 1990s, such as the current U.S. civilian time standard clock, the NIST-F1 cesium fountain clock. The strontium lattice clock and some other experimental clocks operate at optical frequencies, much higher than the microwave frequencies used in cesium clocks. In the past decade, the rapid advances in experimental atomic clocks at NIST and other laboratories around the world have surprised even some of the engineerss leading the research, according to NIST.
The strontium lattice clock may someday be chosen as the new timekeeping standard by the international community, NIST Fellow and group leader, and an author of the article, Jun Ye said in the press release. Ye, in fact, is not satisfied with the awesome level of accuracy his team has already achieved. "We already have plans to push the performance even more," he said in the press release. "In this sense, even this new Nature paper represents only a 'mid-term' report." Next-generation atomic clocks have already contributed to scientific research and are expected to lead to the development of novel technologies such as super-sensors of gravity and temperature.
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