Hyper-precise atomic clock detects tiny changes in the fabric of time

Scientists have created an optical lattice atomic clock so sensitive

that its timekeeping is affected by gravitational changes due to height

differences of as little as 2 centimeters. (Ye group and Steve Burrows /

JILA)

Excerpt from latimes.com
By Deborah Netburn


Scientists have created an atomic clock that is so precise that

it can detect tiny changes in the speed of its ticks depending on

whether it is 2 centimeters closer or farther from the center of Earth. 

“Time

can be intricately connected to gravity,” said Jun Ye, a physicist

at JILA, a joint institute of the National Institute of Standards and

Technology and the University of Colorado, Boulder. “It sounds like

science fiction, but these measurements are a reality.”

The

ability of a hyper-sensitive clock to determine small differences in

altitude is based on Einstein’s prediction that the farther one gets

from the center of an attractor (like Earth), the faster time moves. 

Researchers

have long ago proved this theory by comparing the speed of clocks

separated by vast differences, either on board satellites in orbits

a few dozen miles apart, or by comparing the ticks of clocks telling

time at sea level and those placed on a mountain top. 
 
Five years

ago researchers at NIST created a clock so sensitive that it could

detect the difference in time between two elevations just a foot from

each other.

But the new clock is even better. 

“Now

when we measure this very weird property of time fabric in the

laboratory, even a 2-centimeter change will result in a detectable time

change in the clock,” Ye said.

The clock is described Tuesday in Nature Communications. It is a tweaked version of an optical lattice clock that measures the oscillations of strontium atoms that have been trapped in a network of lasers. 

Ye,

who is the principal investigator on the paper, explains that the clock

measures the speed of an electron as it zips around the nucleus of

a strontium atom at the rate of about a million billion orbits per

second.  

To calculate this movement, the researchers hit a few

thousand strontium atoms at a time with what they call a “clock laser.”

The laser can be tuned so that the peaks and troughs in its electric

field match the oscillation of the electrons of the strontium atoms.

The

result is a clock that is several orders of magnitude more accurate

than the cesium microwave clock that governs official time today.

“The

clock we use now is like a watch with a hand that moves 9 billion times

per second,” Ye said. “The ‘watch’ we are working on moves at the speed

of a million billion times per second;  we are basically keeping track

of ripples of light.”

In

this latest iteration of the optical lattice clock, researchers reduced

time-telling errors by installing highly sensitive thermometers around

the trapped atoms so the effects of heat from the surrounding

environment could be better measured. They were also able to reduce the

effects of the laser net on the individual atoms, and they used one of

the most stable lasers in the world to take the measure of the electron

movement. 

These tweaks lead to a clock that is at least three

times more precise than the previous world-record holder introduced last

year, as well as increased stability of 50%. The authors are

anticipating continued progress. 

A clock with this extreme level

of precision may seem like overkill, but it could be used to improve our

understanding of the shape of Earth, help to conduct tests of the

fundamental laws that govern space and time, and provide a new pathway

for investigating dark matter.

And the possibilities grow as the clocks grow more precise.
“If

we can make a clock 1,000 times more accurate, we could hear the

symphony of the universe,” Ye said. “For instance, you would sense how

space time shifts when a distant galaxy explodes.”

Source Article from http://feedproxy.google.com/~r/AscensionEarth2012/~3/Mv4h8NVixbc/hyper-precise-atomic-clock-detects-tiny.html

[ Add Comment ]

Hyper-precise atomic clock detects tiny changes in the fabric of time