An Optical-Tweezer Clock

Apropos of a New Year, Father Time might now carry a third, more accurate type of optical clock—though research, rather than strictly timekeeping, may be its ultimate purpose. Scientists at the California Institute of Technology (Caltech) and NASA’s Jet Propulsion Laboratory, USA, have reported a prototype atomic-array optical clock that uses optical-tweezer technology to combine the benefits of single-atom and optical-lattice clocks.

At present, the most accurate and stable optical clocks use optical interrogation of either a single ion or an ensemble of neutral atoms confined in an optical lattice (see “Toward the Optical Second,” OPN, February 2019). They have enabled new experiments in geodesy, fundamental physics and quantum many-body physics.

The Caltech prototype optical clock platform is based on an array of about 40 strontium atoms, each one trapped by an optical tweezer. The researchers load the array from a cold atomic cloud and then induce light-assisted collisions to eliminate higher trap occupancies.

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