Incredibly accurate atomic clocks may detect faint signals from dark matter

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Atomic clocks are nothing new, these timepieces have been around for many years. Scientists working on experimental atomic clocks at the National Institute of Standards and Technology (NIST) have reported three new performance records for their clocks. The team says that the clocks have improved accuracy enough that not only are they going to improve timekeeping and navigation, but they may be sensitive enough to detect faint signals from gravity, the early universe, and dark matter.

Each of the new atomic clocks traps a thousand ytterbium atoms in grids that are made of laser beams. The atoms tick by switching between two energy levels. The researchers can compare the two independent clocks allowing them to improve systematic uncertainty, stability, and reproducibility.

Systematic uncertainty is how well the clock can represent the natural vibrations of the atoms captured in the laser lattice. The team found the clock had a possible error of one billionth of a billionth from the natural ticking frequency of the atoms. Stability is how much the clock frequency changes over time, in this case, it changes 0.00000000000000000032 during a day. Reproducibility is how close the two clocks tick at the same frequency, the frequency difference was less than one billionth of a billionth in this test.

The ytterbium atomic clocks exceed the conventional capability to measure the shape of the Earth (geodetic measurement) based on tidal gauge surveys of sea level. Researchers say that a comparison of these clocks located far apart, on different continents, could provide geodetic measurements within 1 centimeter, better than the current several centimeters.

Some of the improvements to the new clock include thermal and electric shielding that surrounds atoms to protect them from stray electric fields. Ytterbium atoms are one of the potential candidates to be used in the future redefinition of the second. Scientists are currently redefining all sorts of measurements, including a recent redefinition of how to describe a kilogram.

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