Atomic fountain
Encyclopedia
An atomic fountain is a cloud of atoms that are tossed upwards by lasers in the Earth's gravitational field. If visible, it would resemble the water in a fountain. While weightless in the toss, the atoms are measured to set the frequency of an atomic clock
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Atomic clock
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...
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