how stable are NIST’s chip-scale atomic clocks?
The chip-scale atomic clocks being made at NIST are stable to better than one part in ten billion when timing events over one second. This is equivalent to neither gaining nor loosing one second over 300 years. By comparison quartz crystal oscillators, often found in wristwatches, are stable to about 1 second over a few days. High-performance laboratory atomic clocks are stable to one second over 100 million years. How small are the NIST chip-scale atomic clocks? The physics packages being built at NIST measure 1.5 mm x 1.5 mm x 4.2 mm (1 mm is 40 thousands of an inch), or about the size of a grain of rice. The cell that contains the atoms is about the size of a grain of sand and contains about one billion cesium atoms in vapor form. Is there anything unique about the way these chip-scale atomic clocks are made? Yes! All atomic clocks until now have been built by fabricating individual components (atomic cells, lamp, control circuit board, etc.) and assembling them one-by-one into comp
