Scientists have made an atomic clock so stable and precise that it will not lose or gain a second in 15 billion years, or longer than the time that the universe is believed to have existed.
The strontium lattice atomic clock, which was described in the journal Nature Communications on April 21, is about thrice as precise as the previous record holder. It can reveal tiny shifts in time as predicted by Albert Einstein's theory of relativity, which states time moves faster the farther one gets from the center of the Earth.
Raising the clock 2 centimeters (.79 inches) from the surface, for instance, would affect its ticking rate because of the weaker pull of the Earth's gravitational field. Such precision could be of great help to scientists creating ultradetailed maps of the Earth's shape.
"Time can be intricately connected to gravity," said physicist Jun Ye from JILA, an institute established by the National Institute of Standards and Technology and University of Colorado. "It sounds like science fiction, but these measurements are a reality."
The advances of this optical lattice clock, which measures the oscillations of strontium atoms trapped in a laser network, is a step closer to replacing the cesium fountain clock, which is currently considered the gold standard in timekeeping and is used to set the official world time. An improvement was also made on how closely the ticks match each other, known as the clock's stability, by nearly 50 percent.
"Our Sr optical lattice clock now achieves fractional stability of 2.2 × 10-16 at 1 s," Ye and colleagues wrote. "With this improved stability, we perform a new accuracy evaluation of our clock, reducing many systematic uncertainties that limited our previous measurements."
Ye said that the clock measures an electron's speed as it zips around the strontium atom's nucleus. The researchers were able to calculate this movement by hitting strontium atoms with a clock laser, which can be tuned so the peaks and troughs in its electric field are the same as the oscillation of the strontium atoms' electrons. Ye compared the new clock to a watch that has the ability to move 9 billion times per second.
The team also built a radiation shield around the clock's atom chamber so it can be operated at room temperature and would not be constrained in cryogenic conditions. Ye said that the clock can be operated in simple and normal configurations.
