Atomic clock

An atomic clock is a type of clock that uses an atomic resonance frequency standard as its counter. Early atomic clocks were masers with attached equipment. Today's best atomic frequency standards (or clocks) are based on more advanced physics involving cold atoms and atomic fountains.

Research

Most research focuses on way to make the clocks smaller, cheaper, more accurate, and more reliable. These goals usually conflict.

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A lot of research currently focuses on various sorts of ion traps. Theoretically, a single ion suspended electromagnetically could be observed for very long periods, increasing the accuracy of the clock, while also reducing its size and power.

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In practice, single-ion clocks have poor short term accuracy because the ion moves so much. Current research uses laser cooling of ions, with optical resonators to increase the short term stability of the driving optics. Much of the difficulty is related to eliminating temperature and mechanical noise effects in the resonators and lasers. No laser has achieved wide use. The result is that the ion trap is very small, but the supporting equipment is still large.

Related Topics:
Laser cooling - Noise effects

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Some researchers developed clocks with different geometries of ion traps, as well. Linear clouds of ions have better short term accuracy than single ions. There are trade-offs.

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The best developed systems use Mercury ions. Some researchers experiment with other ions. A particular isotope of Ytterbium has a particularly precise resonant frequency in one of its hyperfine transitions. Strontium has a hyperfine transition that is not as precise, but can be driven by solid-state lasers. This might permit a very inexpensive, long-lasting compact clock.

Related Topics:
Mercury - Ytterbium - Strontium

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